Read that again and think about the implication of what you've written.
Mueller is not investigating President Trump.
You - “Mueller is not investigating President Trump.”
Fact - “Mueller was authorized to investigate “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump.” http://www.washingtonexaminer.com/byron-york-mueller-does-what-special-prosecutors-do/article/2639509
So you’re off on that one.
So again, show me where the Constitution authorizes the President to appoint a special prosecutor to investigate ANYBODY, much less the President himself ESPECIALLY when there’s no reasonable suspicion or probable cause.
The ONLY branch authorized to impeach, which presumptively would include any necessary investigations based on reasonable suspicion or probable cause, is CONGRESS, NOT the President.