Login box

I was sitting at my buddy's computer on the phone and
typed in my name and access password. To my surprise it
signed me on the computer. Now my name keeps popping up
on his ctrl/alt/del box when I reboot the computer. I
don't want him mad at me. How do I get my name off the
box?

Is there no one that can help? I just want to remove my
name from his drop down on the login box