It's not mybb's job to keep him off the computer. Not to mention to make sure he doesn't share his password.
Nayar just do what i did, insult someone enough to get a warning, feel free to insult me, if that helps you get your goal.
SHHH! You should have pmed him that. Now they'll just delete the post, knowing he's doing it on purpose
Seriously, just study. Lock your computer, ask your parents to hide the keyboard and the mouse, and maybe turn off the internet. No need to ask for a ban.