annul

(verb) declare invalid. Synonyms: invalidate, quash, void, avoid, nullify. Examples: "The contract was annulled." "Void a plea."

(verb) cancel officially. Synonyms: revoke, lift, countermand, reverse, repeal, overturn, rescind, vacate. Examples: "He revoked the ban on smoking." "Lift an embargo." "Vacate a death sentence."