I am sorry but I would either rehome him or roast him although maybe you can try to teach him whos boss but I doubt that would work since he's mean to the other chickens too I think it like only works if he's mean to people but I don't know maybe not but I would not risk it and either way I would get rid of him ASAP exspecially if he's attcking your kids too that to me is the end of the line. I would get rid of him ASAP wheather u rehome him or roast him. good luck.