How to completely wipe a hard drive for a new computer build?

[Lookin4Info]

My friend is building an entirely new computer and he's going to use the hard drive from his old computer that he bought at Bestbuy. So my question is, how can he completely delete everything on the hard drive so he can install Windows 10 on it? Can he just go to "This PC" and format every partition? Also, is it true that you can download Windows 10 off of Microsoft's website and use it without having a CD key?

 

[Barty1884]

1. You cannot format a drive you're currently booting from - if it's currently secondary storage, you can via disk management (but he's installing W10 to it, so I asusme it's a boot drive).

2. You can simply delete partitions/format at the point of install - I would suggest writing zeros over it if he were giving it away, but reusing yourself, deleting the partition is all that's necessary.

3. You can download the ISO and install, but that doesn't provide activation. A seperate key is still requied*.

3.1*. IF your friend is currently running W10, you can link that to your MS account and then install/activate following a "hardware change" .

 

[SkyNetRising]

how can he completely delete everything on the hard drive so he can install Windows 10 on it?

Clean the drive using diskpart (accessible via command prompt when booting from windows installation media).

Also, is it true that you can download Windows 10 off of Microsoft's website and use it without having a CD key?

Yes, but it will be unactivated - with limited features and will nag you about activation.