renege

chicken (out), wimp out

backpedal, backtrack

disavow, forswear (also foreswear), recall, recant, repudiate, retract, take back, unsay, withdraw

beg off

contradict, deny, disavow, disclaim, disown, gainsay, negate, negative

abandon, bolt, forsake, give up, relinquish, spurn, surrender

controvert, disagree (with), disprove, dispute, rebut, refute

back down, back off, backtrack

disallow, recall, revoke