Logon Screen Been Gayed

My father went onto my computer in safemode and used the administrator account that I forgot to password to make an account for himself while I was away. He claims he deleted it after he used it for getting a file off my computer. Now however when I am logged on if I go to log off and then switch user, in the bottom corner instead of saying Turn off "My computer name" it says Turn off "joe-temp". Is there a way to change it back?

I got it. I try not to fuck with windows because although I use it, I know that if I change the tiniest setting windows will destroy itself.