Removing someone from Family Sharing

I don't know, but I'd guess probably, and probably not. They are going to find out next time they try to buy something, use a shared service, or download a past purchase from someone else in the family. See Leave Family Sharing - Apple Support for the process, if not all of the consequences.

tt2

I too suspect they would be notified. In the document to which a link was posted, Apple doesn't mention what happens, which would point to it not being a configurable option. It would also make sense for them to be notified instead of discovering out of the blue they were no longer part of the sharing group. This would be particularly critical if they were part of an iCloud storage subscription being shared beause they would need to be notified as soon as possible about having to get their own subscription or else risk losing files.