Hitler's plan for Moscow was to kill all its residents and cover it with an artificial lake.
Hitler had some radical ideas prepared for Western Europe after he'd won World War II, but these plans were all pretty tame compared to what he had come up with for Russia and Eastern Europe. His intentions for this part of the world were merciless if not fiendish and probably qualified as insane.
One of the cornerstones of the Nazi expansionist policy was known as Lebensraum, and it formed an important component of the Generalplan Ost, or "Master Plan for the East." In this scheme, all the indigenous Slavic people would be removed permanently or enslaved. This included the Poles, Ukrainians, Russians, and any other Slavic people, who were, according to Nazi ideology, considered inferior to the Aryans. As they were thought of as a racially inferior people, they were deemed expendable.
Lebensraum dictated that the superior Aryan race had the right to remove anyone of an inferior racial descent, for the sake of providing Aryan living space. The Slavic peoples of Eastern Europe would have to be exterminated by enslavement and mass deportation beyond the Urals to Siberia, or they would simply be starved to death because their agricultural output would be diverted to feed the German people.