I'm not 100% sure but I think it's something like this: Go back into users, clear any names that are in there, I think if you just leave it blank and re-boot, it should be o.k.
I could be wrong, it's a long time since I messed around in there, but it's worth a shot.
By the way, when you ask a question like that, don't forget to say which operating system you are using.