>Law governing removal of a sitting Congress
Under Article I, Section 5, clause 2, of the Constitution, a Member of Congress may be removed from office before the normal expiration of his or her constitutional term by an “expulsion” from the Senate (if a Senator) or from the House of Representatives (if a Representative) upon a formal vote on a resolution agreed to by two-thirds of the Members of that body present and voting
If not all S/HOR are present during the vote then the 2/3 requirement has a lower number needed. There was a meme before to show the math I just can't recall the numbers.