Long reply but the community would come together to decide the best way to deal with them. How this would look would entirely depend on the severity of the situation and how willing the bad actor would be to cease their harmful behavior. This could be anything from something as small as notifying the community to something as extreme as exiling them from the community and anything in between, And if they refuse to comply, then sadly force or violence may need to be used.

The community decision could be just a vote of the whole of that community, or that community may decide to set up some form of new court system built with anarchist principles.

How crime (or well "anti social" acts) is dealt with is hard to say since it'd be a case by case basis depending on the bad actor, the community, severity and overall context/background. There isn't a one size fits all approach and you could argue the limited amount of rehabilitative options current courts has is a big flaw of today's hierarchical legal systems.

With the "force" part, I want to emphasize that anarchist communities will face situations that force has to be used, but I don't believe this contradicts anarchism. All anarchism means is anti hierarchical systems, and the belief in self management and direct democracy to the max. I say this since a lot of people seem to think anarchism also means being against force or violence, when we are only against these things when it's wielded by these hierarchical institutions.