Thanks to big data you can do it in a very subtle way. For instance, you can call people for vaccination programme, that will make people from your list of undesirables infertile. This way you won't even have to build concentration camps and you can claim "oopsie daisy it was a bad batch, our bad" etc.

That's a more extreme example, but there are lot of other ways creative government could make the lives of people they don't like miserable or impossible.