Synonyms for Abnegate:

n.

abnegate (noun)
deny.

v.

annul (verb)
divorce, veto, abolish, negate, refute, eradicate, nullify, eliminate, repudiate, extinguish, invalidate, undo, cancel, obliterate, delete, reject, Disaffirm, withdraw, annul, destroy, efface, neutralize, dissolve, dismiss, disclaim, revoke.
confute (verb)
conflict, disprove, rejoin, challenge, repeal, contradict, dispute, confute, rebut, abrogate.
possession (verb)
deny.
renounce (verb)
betray, desert, abdicate, renounce, defect, abandon, retract, disavow, backslide, deny, cross, reject.

Other synonyms:

deny
disclaim, veto.