If "claim" refers to asserting a right or ownership:
* Relinquish: To give up a claim or right.
* Surrender: To give up possession or control.
* Abandon: To leave behind, often without intending to return.
If "claim" refers to stating something as fact:
* Deny: To state that something is not true.
* Dispute: To argue against a claim.
* Contradict: To state the opposite of a claim.
If "claim" refers to demanding something:
* Concede: To admit that something is true.
* Yield: To give in to a demand.
* Compromise: To reach an agreement by giving up something.
To choose the best antonym, consider the specific context of the sentence.