Hi, I'm hoping you can help. I'm trying to get rid of a guest who has outstayed his welcome. I've logged into the account and selected the delete files log out. I've gone into Users & Groups and unselected "Show fast user switching menu as" and restarted the computer. Twice! Still the minus button is greyed out. I've tried Apple Support pages but they're better at telling you how to do something than to undo it.