You can quit a club you joined for the wrong reasons. Joining wasn’t a lifetime vow.

Joining something is not a promise about the rest of the year. Plenty of commitments start for reasons that have nothing to do with the thing itself: a friend was doing it, it looked good on a form, someone asked at the right moment. Staying out of a sense of obligation to your past self is a strange way to spend Thursday evenings. Leaving well is a normal event.

If something you are in has stopped being worth the hours, tell whoever runs it before the next session, briefly and politely. Thank them and go. Then use the freed-up time on purpose, or it will just absorb into the week.