to nullify /ˈnʌlɪfaɪ/ /ˈnʌlɪfaɪ/
to rescind /rɪˈsɪnd/ /rɪˈsɪnd/
to cancel /ˈkænsəl/ /ˈkænsl/
to call off /kɔl ɔf/ /kɔːl ɒf/
to annul /əˈnʌl/ /əˈnʌl/