Troubled teenage boy

Hi my nephew is 15 and lives with my mother (72) he was adopted and he is really bad. On another level bad. He is already 6’200 pounds. He just wants to stay in room, eat, and play video games. My mom took away his games he refuses to go to school. He threw water and my mom and cops were called. How do we get him to go to bootcamp mandatory because a lot of the programs are voluntary and the child has to comply etc. any tips I would appreciate it. My mom lives with such torment he threatens to throw away her food if she doesn’t buy him junk food. He trashes the house leaves toilet seat up without flushing etc