I let my kid quit the week before a performance. And he had my blessing.
He was in a program called Band Builders. A local music school matches kids up with others of comparable ability and interests to form rock bands. Each band learns 3-4 songs and they all gather to perform for a concert at the end. DS had enjoyed previous sessions, but was not progressing in this particular session. I didn't know why. But, I was going to miss the concert, so I asked to watch their final rehearsal. Practice sessions were generally closed to parents, so I had never watched a session before. Well, my eyes were opened as to why DS was not enjoying it. The band coach was horrible! Every word out of his mouth was negative. He was yelling. He would call kids out and belittle them in front of their peers. The kids were obviously not enjoying it.
On the way home, I told DS that he would not be coming back. And I told him why. He does not have to continue to be talked to in that manner. That was not coaching, that was intimidation. I expect a coach to offer constructive criticism, and I expect my kid to be able to accept it and learn from it. But, this guy was bordering on being verbally abusive.
Requiring a kid to honor a commitment is one thing, but requiring him to submit to that type of conditioning is unreasonable.
DS was thrilled to miss the concert. The coach ended up filling in on DS's part. And I could care less.