“Fortunately, the Morgenthau Plan resulted in the postwar deaths of “only” 6 million Germans; not the 25 million which had apparently been planned. As an aside: it should not be thought that those 6 million deaths are the only postwar mass murders for which the Allies were responsible. There were plenty more mass murders in addition to the Morgenthau Plan.”
Quote from Wikipedia
"Unhappy with the Morgenthau-plan consequences, former U.S. President Herbert Hoover remarked in a report dated 18 March 1947:
“There is the illusion that the New Germany left after the annexations can be reduced to a ‘pastoral state’. It cannot be done unless we exterminate or move 25,000,000 people out of it.” 
It is argued that it was Hoover’s March 1947 statements in his report that led to the end of the Morgenthau plan and to a change in U.S. policy."
Hoover is not advocating for the extermination of 25,000,000 Germans, he is rejecting the Morgenthau plan.