You should rename the user it self and not the folder.
If you really want to rename the folder you should take over owner ship.
Go to properties - security - advance - ownership. Make your self the owner and remember to give yourself full control.
If that fails there is a good program called unlocker. Here is it: UNLOCKER 1.9.2 BY CEDRICK 'NITCH' COLLOMB
Yeah that's what confuses me aswell.
The unlocker program should do the trick though.
He should be able to rename it after the program has done it's magic.