to say that (something) is not true

disagree, renounce, decline

to refuse officially to allow or accept (something) as correct

reject, prohibit

to say that one does not own for have a connection with (a person, thing, action etc)

deny

to say that one does not know, that one has not or no longer wishes to have, any connection with (a person or thing)

refuse to acknowledge

to give up (an opinion, a belief) publicly; admit (a statement) was false

take back something said

to declare formally that one will no longer have anything to do with (a person, belief etc)

abandon, reject

to refuse to accept or acknowledge (something); to refuse to pay (a debt)

reject; turn one's back on

to take back or withdraw (a statement, offer, opinion etc)

take back; renege on