He needs to get into counseling. If he remains this way it will only get worse and then in a couple of years the parents will have NO control over him.
Something has to be troubling him. If he is open and communicates with you maybe you could have a heart to heart talk with him. I am thinking you may have a good relationship since you say how to help him with anger management?
Basically get him to realize he needs to stop and take a breath, calm down and rationalize the issues and the options of dealing with the problem in a more positive way and using a positive approach. Get him to realize that anger doesn't accomplish anything it often only creates more negative issues in the long run.
Maybe think of some examples and outcomes both negative and positive that he can relate to with his anger. Get him thinking through problem solving and conflict resolution.
Here are some things you can read through that might help
dealing with anger - Google Search coping with anger - Google Search anger management - Google Search problem solving and conflict resolution with anger - Google Search