throw in the towel
Definition from Wiktionary, the free dictionary
From the traditional signal from a boxer's support staff of throwing such an item into a boxing ring to indicate that the contestant cannot continue the match and is forfeiting to the opponent.
- (idiomatic) To quit; to give up.
- If their restaurant can't get business even on Mother's Day, it might be time for them to throw in the towel.
(idiomatic) to quit; to give up