Q137. "I recently had a debate with a friend of mine. The question was what is required to repeal an Amendment to the Constitution. I told him I thought it would take two-thirds approval of the House and Senate, the President's signature and three-fourths approval of the states. Was I right?"
A. The repeal of any part of the Constitution requires an amendment to the Constitution — this includes the repeal of a previously passed amendment. So, the process is well defined in the Constitution, and is detailed on the Amendment Page. In reading that page, you can see that you were almost right — the biggest mistake you made is that the President is not involved in the amendment process in any way.