The Congress can, with a simple majority in the House and 2/3 of Senators present in agreement, remove any President for any reason.
The fact that they have never done so indicates that trivial reasons such as political disagreements probably will not suffice.
And, by the way, the Supreme Court and all inferior courts have NOTHING TO DO with the Congressional power of impeachment and removal, with the single exception that the Chief Justice of the United States is the presiding officer when the President is on trial.
Nothing the Congress does or does not do with this plenary power is reviewable by any court.