That blows man. I don't know what grade your in but one of my best friends decided he was gonna drop out like a month before we graduated. SOOO dumb. Some people think they don't need a high school diploma, but when they get out in the real world and they may wake up one day and say "damn i wish i could go to college." Don't push to hard on him cuz he might become angry with you (my friend did when a group of us tried an intervention), but try tho. If hes really stuck on dropping out I'd say try to respect his decision no matter how hard it is for you to do.
I wish you Good Luck with it!
-Justin