Not sure what to do about my sons friend.

My 6 year old son has this friend that I’ve had nothing but problems with this past year. Anytime he gets mad at my son he starts trying to hit and kick him and after giving him one chance I send him home and tell his parents what happened but it almost seems like they think their child can do no wrong. I have also had problems with this child talking back to me and he even threw his dirty socks at my husband one time because we had told him it was time to leave and he of course got mad. I’ve told his parents everything and they don’t seem to care. They also get in fights constantly on the bus. I’m at a point where I just don’t want my son playing with him anymore but my son really likes playing with him for some reason. Would I be wrong for distancing my son from this kid and making him play with the other kids in the neighborhood? I feel bad but I just feel like this kid is to much. Thanks.