I covered this a little in own of my most recent posts; essentially the individual is resstrained and given the chance to apply to other communities/areas to be released to, and if they are not accepted they can go into a non-occupied zone, out of the boarders of the anarchist territories, or get the punishment the community decides on, which could be death or simply starting at the bottom and living with no luxuries.
In "an"caps, well, you just get shot by the landowner or enslaved by their private police force :)
So a non occupied zone would be basically wildlands? away from society?
Theoretically, yes, although this could present issues with people trying to set up road-blocks and that'd result in a violation of the NAP, and likely extreme violence, but that could easily be solved by designating where the wildlands is.
It could simply be different parts that are unpopulated all around the world. If the USA flips, allow part of Alaska, a good chunk of the Dakotas, and potentially a slot somewhere on the southern boarder where it's agreed to simply let criminals do criminal things there, or for them to build their own society and potentially redeem their self as individuals, promoting other communities to accept them in again.
Essentially it's immoral to hold someone indefinitely and give them no other choice, even if they committed an awful crime, plus it wastes surplus, so offer him to other people and if nobody wants him give him the choice between the societies punishment/reform or being released into a wild-land with just some basic supplies appropriate for the climate.
Well I guess I will leave it at that, the answers certainly don't convince me.