Complex sentence: Morton went with Letterman to CBS in 1993 to serve as executive producer of CBS' "Late Show with David Letterman", but left the show in 1996 after trying to move the show to ABC and upsetting Letterman as a result.
Split into simpler sentences: Morton went with Letterman to CBS in 1993 to serve as executive producer of CBS' Late Show with David Letterman from 1993 to 1996. He left the show in 1996 after trying to move the show to ABC and upsetting Letterman as a result.