I would find out why he does not want to go back to school. Is he being bullied? Does he not feel as if he fits in? Had a bad experience with a girl? Running away from the problem does not help painful as it might be.
Not wanting to go to high school is something that many teens don't want to do but need to. It's part of growing up and learning to get along with people. I still have high school friends from over 30 years ago. Does he not have friends, not do sports, not belong to any clubs, not want to go to college?
What happens when he decides he does not want to go to work because he is being bullied or unhappy? Most teenage boys have tons of friends to hang out with and do things with. My boys always had friends over.
Perhaps some therapy is needed.
Perhaps he is in pain and afraid. I would give him lots of love, support, therapy and not let him quit high school but find the true root of the problem. Best of luck to you and him.