Similar sort of problem, tried to set up No Passwords but it insists on a password and says it is wrong (but it isn't). Then I can get into another "me" but only with a PIN. I cannot delete the first "me" or get into it but in Users only one"me" appears. There is no built in Admin account that I can see.
It is driving me nuts to have 2 "me"s and the constant requests for login passwords/PINs.
As other people have said if someone else is trying to get onto my Desktop then my house is being burgled and I have bigger problems!!