If that's what it takes to get him to obey then I would do it. I also like Glenda W's suggestion. We used to use those threats with my oldest son and the mere thought of me walking him to class or showing up at lunch was a great motivator to get him on the straight and narrow.
Depending on the child's maturity level (my son was more immature so it happened later rather than earlier), this could be the age where this kind of thing starts for him (rebellion). If it is, things will be a struggle from this point forward, so you have to be prepared to follow thru with whatever you "threaten" him with. If you're not consistent each and every time, he will totally play you and it just gets worse. You have to remember the punishment has to fit the crime so you can't reasonably ground for a month 'cause they lose hope and don't have anything to work towards. But taking away privileges away for a week or two weeks, like TV, phone, going to their friend's houses or their friend's coming over, etc., can help. We would also give our son opportunities to earn his privileges back when he was grounded one at a time so his grounding would be shorter than planned, but he would have to do things, i.e., get an A on an upcoming test, turn in his homework every day for a week, etc., to get one of his privilges back. That seemed to help. I think they need something concrete to work towards sometimes. Other times, it's a shot in the wind and nothing seems to work.
Just be consistent, caring and consistent (yes, I know I said that twice). That's the most important thing. And as far as the hair goes, hopefully the threat of losing it will get him going in the right direction. Good luck!