turnabout, reversion, turnaround, reversal, reverse - turning in the opposite direction

change - the action of changing something; "the change of government had no impact on the economy"; "his change on abortion cost him the election"

undoing - an act that makes a previous act of no effect (as if not done)

turn - change orientation or direction, also in the abstract sense; "Turn towards me"; "The mugger turned and fled before I could see his face"; "She turned from herself and learned to listen to others' needs"

rethink - change one's mind; "He rethought his decision to take a vacation"