How can I re-format my internal hard drive so I can do a clean re-install of my OS (windows 8)?

The installation does not give me the option to "delete all drives." It basically has these options:
1. Install Windows 8 (I tried this. Turns out this does NOT format the drive first, or erase the existing content, to my surprise).
2. Repair/Refresh drive (Deletes any user-installed apps, may set some settings back to factory, but does not delete your programs or files on the drive. Does not seem to do what I want, so I have not tried it.)
3. Repair/Reset drive (Restore computer to factory-new condition, deletes all user-added settings/software. However, does not reformat the drive -- you can actually do this FROM the drive itself.)

Your reply seems to assume that having a boot/installation disk allows you to reformat the internal disk. THAT'S EXACTLY WHAT I THOUGHT, that's the whole point of my question... I thought that was true, and apparently I'm not alone, but I cannot for the life of me find it. Both the "Install" DVD-Rom and the Recovery Flash Drive give me a limited menu of the above three options, and if I don't select one of them, it then proceeds to boot up from the internal drive. And I obviously cannot re-format the internal drive when I'm using the OS on the internal drive.

Thanks anyway...

Still looking for answers...

I don't understand your instructions. I booted from the installation DVD-Rom, and I selected "install." There was no "clean install" option.

I'm confused what you mean when you say "after that" you can see all the drives/partitions and delete... Ummm... You mean AFTER I install (reinstall) Windows 8 on my internal drive, then I'll be able to delete everything on that drive? That does not make sense. Are you talking about creating a partition on the internal drive, installing the OS into one of the partitions, and then deleting the other? Cause that's not what I want. I want to format the whole drive, not just a part of it.

Still seeking an answer in plain English that I can understand.

Okay, I went back into install and this time I did find a way to select and reformat the internal drive from there, then got an error that partitions were not ready or something. Found a solution for that through googling and used the disk repair option from the boot disk to fix that, and then was able to install Windows 8. So it was a success.

Alas, now it is telling me that I cannot activate my Windows 8 Pro. As best I can figure, when I upgraded from Vista to Windows 8, I bought an "upgrade" license. And since the installer does not see an old Windows version on the drive, it is treating me like a pirate and the software will disable in 30 days.

While I understand why this is happening, there is one very annoying aspect: This windows 8 boot disk is not something I physically purchased. I purchased a Windows 8 download, and after it upgraded and installed to my computer, I followed the recommended instructions to create a Boot disk. That is the disk I am using now. So this disk was created by my Windows 8 AFTER it installed itself over my old Windows Vista. So how hard would it have been for Microsoft to make it so that AFTER your Windows 8 upgrades your system over an existing Windows version, it will NOTE that fact on any subsequent boot / recovery disks or drives it might generate, so it does not make the EXACT mistake it is now making, basically robbing me of the license I paid for simply because I wanted to do a clean re-install of the software. From my googling, a LOT of people have run into this problem upgrading to a new Windows version, then later having to repair / wipe their drive and reinstall it, and then suddenly being treated like a software pirate with no good solution but to purchase a new "non-upgrade" Windows license. That is Evil Corporate Customer Disservice.

Now, I think I know the "fix" for it. I have to dig out my REAL old Vista recovery disks, then reinstall Vista on my computer, THEN use the Windows 8 Recovery Disk to install it on the computer over Vista. Presumably then it will accept my license. Of course, that'll flush another dozen hours down the drain. But Microsoft does not care about my time, right? They're hoping I lost my Vista recovery disks so they can make another sale.

Thanks to all who chimed in with help. Sorry I was kind of dense about it.

Ken