Assuming that there's actually a problem rather than crime reports being fabricated or exaggerated by those that want to promote genocide, and that there's actually a desire to deal with it by means other than gratuitous state violence:

It turns out that you're not the first to ask this question and there is a small but determined body of both academic and military research into how to do de-radicalisation. e.g. https://www.flemishpeaceinstitute.eu/sites/vlaamsvredesinsti...

Note that this study often puts material conditions at the root; so long as a group really is disadvantaged and marginalised to their detriment, there's always going to be some politics which can lead to radicalisation.