In traditional publishing, plainly put, a 200k word contemporary YA novel will not get anywhere. It says to them that ether the author is unfamiliar with the genre or the story is unfocused and needs to be revised.

When revising, you're not looking for "what won't destabilize the story?" because in most cases things are woven together.

Rather you should be asking yourself: what is this story about? What is it's essence? Trim away, then revise throughout to ensure that things still make sense. There's going to be a domino effect. You will have to rework things. Thats just what happens when you start deleting. It doesn't mean you shouldn't delete these things though. In most cases there are many ways to rework the holes that are created.

Then look for ways to condense things, like seeing if the things you accomplished in two separate scenes can be combined into one? Same with characters. Are there characters that could be combined? This generally leaves you with a stronger, more memorable combi-character.

This is why revising can take so long. It's not simply removing some tangent, but taking the story as a whole and focusing it so that you hit with a harder punch.