ClearName

ClearName is a free tool that permits you to wipe out the last logged in user name from the Windows login prompt
ClearName is a free tool that permits you to wipe out the last logged in user name from the Windows login prompt. If you are concerned with security or just want to "hide your tracks", just add ClearName to your login script.

ClearName runs in invisibly, so when you launch it you never see a thing happen. Once ClearName erases the last login name, it closes down.