Deleting User Profiles
User profiles consist of a combination of folders, files, and registry settings. If you try and delete a user profile by selecting the user's main profile folder in Windows Explorer and clicking Delete, this will delete the folders and files associated with the profile but not its registry settings. This can result in strange things happening, for example if a user tries to log on using such a profile, she may see an error message saying that Windows could not find her user profile and is logging her on with a temporary profile.
The correct way to delete a user profile that is no longer needed is to do the following in Vista: click Start, right-click on Computer, select Properties, click Advanced System Settings, select User Profiles, click Settings, select the profile and click Delete.