The two MLB managers that have won the most World Series in the American League are Joe McCarthy with 7 World Series wins with the New York Yankees (1932, 1936-39, 1941, 1943), and Casey Stengel with the New York Yankees (1949-53, 1956, 1958).
The MLB manager that has won the most World Series in the National League is Walter Alston with 4 World Series wins with the Dodgers (1955, 1959, 1963, 1965)/