OK, so all police pull out of all black neighborhoods and cities, stay in the police station. If any poor slob has a black crime to report, have them come on down and fill in a some paperwork.
Pushing those neighborhoods to a militia system might not be the very worst thing in the world for them... though things could get, er, INTERESTING before they settled down. They’d off a bunch of malefactors of their own color (nobody would say squat about it) then there would be an uneasy peace.