A senator or congressman can be removed by death, resignation, defeat in an election or expulsion by a two thirds vote of the House in which the individual is a member. That’s basically it.
Sigh.
But maybe we can recall them. While there's no mechanism in the Constitution to recall congressional members, neither does the Constitution prohibit it. As Justice Clarence Thomas argued in U.S. Term Limits, Inc. v. Thornton: "where the Constitution is silent, it raises no bar to action by the States or the people."
Democrats Are Watering Down Impeachment into a Mere Recall Effort