No one. All his cabinet members continued to serve on in the Ford administration. Now I guess we can say that Richard Kliendiest (?), Elliot Richardson went down because they refused to cooperate with the Watergate cover up. The Chief of Staff can be considered a part of the President's cabinet, I certainly do considering the position's intimate relationship with the Office of the President, although you don't often see the position listed as part of the traditional cabinet. Bill Halderman, Nixon's Chief of Staff also went down due to Watergate.