Would it be good to have a Constitutional Amendment to give voters the right to recall embarrassing Senators and Congressmen?

That's up to the States! But I won't oppose such an Amendment!

Trump is the most embarrassing person in the history of politics.

They do have that right. It's called a "recall election".

We need one to get rid of a nincompoop in the Oval office.

You do not need one. Each state has recall procedures. Not knowing what side you are on makes it hard to decide if you are the embarrassment or the candidate.