Unable to delete user on MacBook
I just had this exact issue also. When I couldn't delete the user the normal way, I tried deleting the user home folder. That didn't help... home folder gone but user still showing in System Preferences/Users & Groups.
Just for the **** of it I tried horsing around with the parental controls for the unwanted user. I unchecked "Limit Mail" and "Allow use of camera", and then for some unknown reason I was able to delete the user. Who knows?