Tip: Deleteting an old user account folder that cannot be deleted in Windows 7
Start first with starting Command Prompt as Administrator. (in Accessories).
Next, for example, if I wanted to delete a folder named Folder on my desktop, I would type this command below.
RD /S /Q "C:UsersUserNameDesktopFolder"
To delete a user fold called Bert, I would type:
RD /S /Q "C:UsersBert"