renege

chicken (out), wimp out

backpedal, backtrack

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

beg off, cry off [chiefly British]

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