In general, I believe that great care should be used when redirecting repetitive behaviors. I do think they serve a sensory need, and based on my reading I think if you try to extinguish them without replacing them with something, the child is apt to miss a type of regulation they need, and or possibly develop a more harmful one to replace it.
If a repetitive action is self-harming or to dangerous to others that is a whole other thing, and in that case it needs to be prioritized, but I still think you have to find something to replace it that the child will accept, that is not harmful, obviously.
If they are harmful in less obvious ways (like socially or academically) that is a tough one b/c obviously no one wants his/her child picked on, or having to be removed from class for disruptive stims) but on the other hand you have to make sure the child's regulation needs are met. So, I think the idea would be to replace it with something less stigmatizing, if possible.
I would not force it, or distress the child unless it is a safety issue.
I know there are also issues where the feeling is that it is self-reinforcing and blocks out time that could be used for acquiring necessary skills. There may be times where you might be able to try to get the child to decrease quantity of stimming and defer it while skills are taught. I really am very conservative about this because I really worry about the child adopting new and harmful stims.