Who did not step in the moon in the mission of Apollo 11?

Michael Collins

Explanation:

Among the three astronauts that went in the Appolo 11 mission to moon. Two of them landed their foot on the moon surface while one of them remained in the lander. His name was Michael Collins.

Michael Collins was command module pilot. While Neil Armstrong and Buzz Aldrin were the other two. Neil Armstrong Was the first to land his foot on the lunar surface.