Nullify

revoke kill undo void invalidate repeal rescind quash ax trash veto abolish wipe out annul negate neutralize offset counteract counterbalance countervail limit restrict scratch scrub squash zap abrogate vitiate annihilate abate take out stamp out blue pencil disannul compensate confine renege renig torpedo wash out bring to naught call all bets off forget it nig render null and void