Windows 7: Deleting extra User Folders and changing permissions

I need to delete some extra User folders which have no users assigned. I've tried deleting them but they give me the following errors:
1st error is "The action can't be completed because the folder or file in it is open in another program"
The strange thing is that there are no users assinged for the folders I'm trying to delete and they are not opened.
2nd error was the fact that it was telling me at one point that I didn't have administrator privilages which is bull, but I think I fixed that by running cmd.exe as admin and putting in the line "net user administrator /active:yes"
The only other problem I also haven't figured out yet is how to change the name of the user folder that the admin account uses. Any ideas on that would be appreciated.