How to delete the Windows directory from an old hard drive?

At least following worked for me:

takeown /f x:\windows /r

added full rights to the folder in properties -> security

icacls x:\windows /reset /T

Download and burn an Ubuntu LiveCD http://www.ubuntu.com/

Then boot into that LiveCD (usually place the CD in the drive, restart your computer while holding down F12 )

The Ubuntu Distribution will take a little while to load, once it does it should recognize your internal hardrives. You can find more info here: http://www.psychocats.net/ubuntu/mountwindows

Just remove these folders through Linux.

rm -rf <path to directory to remove>

if this fails because of privileges try

sudo rm -rf <path to directory to remove>

Be warned, you should be absolutely sure you do not need these directories.

You must take ownership and then grant yourself Full Control permissions to the folder.

Taking ownership only gives you the ability to change ACLs. Granting yourself permissions then gives you the ability to delete the files/folders.