How do you remove Windows XP from a hard drive? Completely wiping it off.

Erm well you can't really.
Yes while it is possible to format your drive this will leave the computer complete non-functional.

If you could explain what you are trying to achieve then we will be able to assist better,

I already have a hard drive with an operating system on it, I just want to use this one as a backup

In that case simply plug it in as a slave and use your current XP to format it.

My Computer > Right click "new" drive > format

Hope this information helps

Uninstalling Windows XP Steps | Uninstalling Windows XP How to. WinXPFix.com

Clean hard drive: reformat hard drive

Oh, I was told not to put in 2 hard drives that each have an operating system.. so yeah ha

Doing a little multi tasking -- hope this helps you wipe the HD

Cnet Video

Completely wiping it off hd - Google Search