How to erase a hard drive after clone?

Format the drive using Disk Management

-Wolf sends

Yep. That's it.

-Wolf sends

After a "quick" format, the data could potentially be recovered. So if you were giving the drive away, you'd probably want to do a more thorough erase so the data isn't recoverable.

If this used to be the OS drive, you also need to wipe the original boot partitions.
Which is not available through a simple format.

You will need to go through diskpart at the commandline.

Delete the original boot partitions, here:
https://social.technet.microsoft.com/Forums/windows/en-US/4f1b84ac-b193-40e3-943a-f45d52e23685/cant-delete-extra-healthy-recovery-partitions-and-healthy-efi-system-partition?forum=w8itproinstall

Formatting won't do what you want, really, but re-Partitioning it will. I think there's third option that is best.

I would recommend that you Zero-Fill that old HDD. Why? Well, that operation writes just zeroes to EVERY sector of the HDD, thus over-writing all data so it is very hard (impossible for an amateur) to recover any old data. That in itself may not matter much to you. But here is what is useful. When you write to a HDD sector, an internal operation that is part of the HDD's own programming will then read back what was written and evaluate the signals. If they are all strong and give correct data, it simply goes on the the next task. BUT if the data are wrong, or the signals from the heads are weak, the system attempts to re-read that data to get a good copy (if possible), then marks that Sector as poor and NEVER to be used again, and replaces it with a good sector from a stock of spares. You see, at the time that the HDD is first Low-Level Formatted at the factory (you cannot do this at home) the HDD has more Sectors than needed for its specified capacity. The known-good un-needed Sectors are logged in a record on the HDD for its own internal use. Having replaced the bad sector with a good spare, the system then will write the recovered data (if it could do that) to this sector. THEN it proceeds to the next operation. So, if you do a Zero Fill, EVERY Sector gets this treatment, so EVERY Sector is tested and ALL weak or failed ones get replaced. When the process is finished, there are NO "Bad Sectors" visible to any outside system, so your OS never knows anything about all this. The HDD appears to be in perfect condition and totally empty, just like brand new from the factory.

Well, not quite. "Brand new" means it has all those spare known-good sectors. But part of the process of testing and self-"fixing" (not really, because it cannot repair a true bad sector, only replace it) is that it also keeps a record of the number of replaced Sectors, and a "brand new" unit has none. There is a limit to how many of these replacements can be done, of course, and that is part of the data tracked by the SMART system. If you ever get a warning message from the HDD SMART system that the number of failed and replaced Sectors is too high, it means two things: your HDD is still working OK, but sometime in the near future it may not have any more good spares to use and cannot "fix" itself; and, the rate of failure may increase, so you should get busy and arrange to replace this HDD before it does actually fail.

So, if you do a Zero Fill it will erase all old data and do a complete test and replacement of weak Sectors. Then you can examine the SMART data from the HDD and verify it still is healthy. THEN you can re-Initialize the unit, knowing it has no faulty Sectors available for your OS to use, and it is still reliable.

One free utility that can do this is DBAN. You also can get free HDD diagnostic suites from the maker of your old HDD. Since it is a Seagate product, download from them their Seatools utility.

Doing a Zero Fill is a LITTLE bit of risk. It destroys every bit of old data, so you MUST be sure what HDD you run it on!! For that reason, personally I like to disconnect ALL other drive units and leave ONLY the one I'm working on attached so I cannot make a mistake. Of course, that means I don't have an Operating System to use. For that reason, I prefer to download the Seatools for DOS version. It is an .iso file, and that means it is a complete image of a bootable CD that you can burn to your own CD-R disk. In fact, you must - you cannot run this file from a hard drive. You download the .iso file. Then you need to get a utility able to burn that file to a CD-R disk - Nero is one such. Burn the CD-R. It is now a bootable disk you work from. Place the CD in your optical drive. Shut down, open and disconnect other drives leaving only the old HDD you want to clean connected. When done, boot into BIOS Setup immediately and go to where you set the Boot Priority Sequence. Set it to boot from the optical drive and nothing else. SAVE and EXIT, and the system will boot from the CD. It loads a mini-OS into RAM and creates a RAM disk for you to store stuff in if you want, then starts up the utility package and presents you with a menu of operations. Verify that it is set to work on the HDD you WANT it to, and not another. Set it to do the Zero Fill and be patient - it takes several hours on a large HDD. When it is done you get back to main menu, where you can see the SMART data displayed. When you are finished, remove the CD and shut down the machine. Disconnect power, open it up, and re-connect all the drives you have to the required ports. Close up, connect power, and boot again into BIOS Setup where you re-specify your desired Boot Priority, and SAVE and EXIT. When the machine has finished booting into your Windows OS, use Disk Management to Create a New Simple Volume on the cleaned-up old Seagate unit. Most default settings are OK. Make sure it uses all of the space available, and you do NOT need it to be a bootable drive unit. I'm guessing you are using the older MBR Partitioning system, but you CAN chose GPT if you wish and if you have the right version of Windows.

Some people are not comfortable doing this that way, and prefer to use the Seatools For Windows version. This can be downloaded and installed on your SSD as a standard Windows application. Then you run it under Windows, but this is REALLY where you MUST be sure when you launch it that it is set to operate on the old Seagate unit you want to wipe, and NOT another. (It will only operate on ONE unit.) Again, after it has finished you back out and use Disk Management to Create a New Simple Volume on the cleaned-up Seagate HDD.

Its simply old gunk that does not need to be there.
After a cloning operation like that, I much prefer to start with a completely clean secondary drive.

Maybe it'll help if I describe what some of these operations do.

A brand new HDD contains circular tracks on each disk surface, and each track is divided into Sectors - many of them per track. A Sector usually holds 512 bytes of data (there are other sizes, too). On a brand new unit, the "data" in ALL those sectors is random junk, with MAYBE a few exceptions on tracks that the HDD does NOT allow some outside agent to access.

The first operation a user does on a new HDD is called Partitioning. This process writes to a specific location at the beginning of the HDD a small set of data files that include a Partition Table (a set of specifications on where each Partition of the HDD beings and ends, and a few details of the type of each Partition) and a small Boot Loader program. One most important piece of data for each Partition in the Table is whether or not this is a BOOT Partition - that is, does it contain an OS that the machine can load and run? The newer GPT system puts more data on the HDD, but it's for much the same purpose. Then it writes a few data bits to places on the HDD that begin and end the first Partition you create with this process, but writes nothing else anywhere. If the first Partition does not use up all of the HDD's space, a subsequent Partition operation can add a new one by entering the correct data in the Partition Table and writing a few data bits to begin and end this new Partition space. The older MBR system allowed up to four Partitions, limited by the size of the Partition Table to hold data. The GPT system allows many more possible Partitions. The MBR system also has a significant limit - its data tables allow specifying where Partitions are only up to a total of 2.1 TB of space. The GPT system uses a different way of storing these location and size data and can allow HUGE total HDD sizes.

The second operation a user does is to Format each Partition that has been created on the HDD. A Format operates only on ONE partition at a time. It writes a set of files to that Partition, starting at its beginning, that create all the file structures needed by the File System you choose for its jobs of managing the use of that Partition's space for files. If you're using Windows in any current form, you almost always use the NTFS File System, but other exist, too. There usually are two options for this operation. A Quick Format does that work and little else. A Full Format does that work, then goes through the entire space of this Partition and tests each Sector by writing to it and reading the data back. If it finds any data errors, it marks the Sector as a Bad Sector not to be used, and keeps that info in a file on that Sector. This is done by the OS, and it's NOT the same system that a HDD does on its own in the background. When a Full Format is complete, every Sector of that Partition has had a test pattern (maybe just zeroes) written to it, but of course that "data" is meaningless.

Modern versions of Windows simplify this process by combining them into one operation called "Create a New Simple Volume". When the two steps are completed, the Partition that results is all ready to accept data, but still contains nothing useful except the "housekeeping" file structures. Very often all of this actually is done as the very first part of Installing an OS, and the third step is to actually copy all the necessary OS files from the Install medium to the HDD, placing certain key files is specific locations with the Partition.

After all that work has been done on a new empty HDD up to the point of installing the OS, the machine can be used. Every time you turn it on, the BIOS goes through a number of start-up operations and finally turns to the process of "booting". It goes to the storage medium you have set in the Boot Priority Sequence and looks for a Partition marked as Bootable. To do that it needs to be able to read the Partition Table of that storage device first, and this is where the change of Partition systems first shows up as an issue. The details of the two ways a Partition Table is constructed are different, so the BIOS needs to know where to look, and how to read the data. The feature called "UEFI Support" in modern BIOS's is what allows a BIOS to access the GPT style of Partition Table. (Access methods for the older MBR style are always included in the BIOS, too.) When it finds a Bootable Partition it then reads the required info from the Root Directory of the File System written in that Partition (it is located at a particular fixed location) and loads and runs the first appropriate files, which leads to further files to load and run, until the entire OS is loaded and operating, ready for user input.

If the HDD is NOT a new empty one but contains one or more Partitions already, each of which has been Formatted and then contain data, the processes are similar. For example, if you Format one Partition, you can choose a Quick Format, which will re-write the Root Directory and blank out all previous records of where data for files was located, but it will NOT actually write anything to all the Sectors that contain that old data. People who want to prevent having their old data found cannot do this alone. A Full Format, on the other hand, WILL write a new test pattern to ALL of the Sectors on this Partition, so it wipes out old data in a way that is VERY difficult to defeat.

A Format, however, is not a Partition Creation. Format works only one one Partition, although many HDD's were originally organized with only one. Re-doing a Partition operation on an HDD, on the other hand. re-writes the Partition Table, thus getting rid of all previous records of where the old Partitions were. Still, if the original organization was not too complex, an expert might be able to find old Partitions, but that's of interest only to those trying to destroy old data.

The Zero Fill operation I recommended in my earlier post is neither of these, and is NOT done by your OS or by the Install process. It is a very different process that specifically fills ALL Sectors of the HDD with zeroes, thus over-writing (and destroying) all old data. But I recommended that for a different reason. Writing to ALL sectors forces the HDD's own internal diagnostic system to test every Sector itself and replace all poor ones with know-good spares. When it is done, the HDD appears to any OS that comes along to have NO Bad Sectors at all, and absolutely no data other than zeroes. So this thorough test-and-"repair" (not really) process is a good one to run on an old used HDD to be SURE it will be reliable before you re-use it.

ref: https://www.lifewire.com/how-to-wipe-a-hard-drive-2624527

To wipe a hard drive means to completely erase the drive of all its information. Deleting everything does not wipe a hard drive and formatting does not [always] wipe a hard drive. You'll need to take an extra step to wipe the hard drive completely. When you format a hard drive or delete a partition, you're usually only deleting the file system, making the data invisible, or no longer blatantly indexed, but not gone. A file recovery program or special hardware can easily recover the information. If you want to make sure that your private information is gone forever, you'll need to wipe the hard drive using special software.

I would pick among the many free one, but best rated one include
http://www.diskwipe.org/
and
https://dban.org/

I honestly don't see why you can't simply format the old HDD and be done with it as Wolfshadow has suggested. We've probably done the same in precise situations like yours a few hundred times with different PC systems and encountered no future problems whatsoever.

Since you're apparently going to retain the HDD as a secondary drive for your own use, i.e., storage, backups, and whatever else you desire, a simple format should be all you need.

If you want to go a step further you can use DiskPart to "clean" the disk and then reinitialize, partition, and format the drive. But frankly, I think even this is unnecessary.

ArtPog, my suggestion is, I realize, more than OP asked. OP asked for the most effective way of removing old files in preparation for re-use. It is clear also that destroying old data for security is NOT a concern here. So, in many ways, Formatting would do that minimal function. (I am not sure about the most recent Windows versions, but older ones would not allow you to Format a HDD that contained a copy of Windows OS.) Beyond what OP asked, I suggested a process to force a thorough test of the entire HDD before relying on it for further use. OP may not feel that is necessary.

Paperdoc:
You're probably correct about a Windows OS restriction that prevents a user from formatting a secondary drive where the drive contains some very old version of some former Windows OS. Frankly I can't recall such a restriction even going back to XP (and even with the Win 95 & Win 98 OS, but I may be wrong about the latter two), but honestly, how many PC users posting to this forum would have versions of those OSs on a HDD they are considering using?.

Now, as I'm sure you are aware, there is a kind of related problem with respect with the Windows OS restricting the user from deleting the Windows OS from a secondary drive. This issue usually arises following the user successfully disk cloning the contents of his/her former boot drive (usually a HDD) to the user's new SSD. (We see this situation nearly every day in some forum post.)

Now the user plans to use the former boot drive as a secondary drive in the system but still desires to retain all the data currently on the drive. To the user's dismay when he/she tries to delete the Windows OS files/folders (and associated data) from the former boot drive since all that data is no longer needed and is taking up valuable disk-space in many cases, the user finds Windows balks at a simple delete process. The deletion process can be done manually as I'm sure you're aware, but for the vast majority of PC users it's a tortuous & complicated process.

(Obviously there's no problem here if the user is comfortable with deleting ALL the data on the secondary drive; a simple format (as we've been discussing) is all that's needed.

But in those situations previously indicated, i.e., just getting rid of the Windows OS files/folders on the secondary drive, we have been advising users to employ the "Take Ownership" process - see https://www.tenforums.com/tutorials/3841-take-ownership-add-context-menu-windows-10-a.html

Possibly you're familiar with it. We've been using this process going back to Win 7, including the Win 8/8.1 & Win 10 programs and it's worked flawlessly the scores of times we've employed it. It does involve a simple registry change which the user can subsequently delete if no longer desired after its use. We leave it be on all our systems and haven't encountered any untoward problems doing so. We highly recommend it.