Complex sentence: In 1969 he returned to the United States after being made Dean of the film school of the California Institute of the Arts, giving up the position in 1978 to become a professor at the school.
Split into simpler sentences: In 1969 he returned to the United States after being made Dean of the film school of the California Institute of the Arts. He gave up the position in 1978 to become a professor at the school.