Removing Trump just after they gave him the nomination a few weeks ago would be political suicide, especially among his supporters. Pressuring to step down is one thing but to remove him is quite another. As I had stated previously; I think those that feel he will eventually step down are correct, but Trump will wait closer to the election to further create chaos for the Republican party going into the general election.
I grant that, but the question was, "could he legally be removed?" The answer is YES and there are still recourses.
The Electoral College. There is no Federal requirement that EC Electors honor their pledges to a candidate; and over the years, a few have voted against their pledge. There are, IIRC a few STATE laws requiring it; but prosecution is unlikely.
The Electors could conspire to not-vote for God the Donald and instead, vote the VP nominee for President.
That kind of organization and collusion working, though, is on the level of herding cats.