The antonyms for "pitch in to" would include words like refuse, neglect, ignore, avoid, resist and shirk. These words refer to actions that are opposite to the idea of contributing, cooperating, or participating in a task with others, which is what "pitching in" means. When someone refuses to pitch in, they are unwilling to lend a helping hand, and when someone neglects their responsibilities, they fail to contribute to the effort. Similarly, if someone resists or ignores the requests of the group to cooperate, they are not pitching in. It is important to have a collaborative effort in society to overcome challenges and problems, and "pitching in" is a key element of that approach.