Complex sentence: Jerry and Charlie O'Connell left the series to pursue film careers, and because Jerry was denied an executive producer credit on the series; when he left, they informed Charlie that they would no longer require him either.
Split into simpler sentences: Jerry and Charlie O'Connell left the series to pursue film careers, and because Jerry was denied an executive producer credit on the series. When he left, they informed Charlie that they would no longer require him either.