Complex sentence: He remained at Upton Park until 1990, a year after the Hammers were relegated to the Second Division, and then signed for Watford, where he played for two years before retiring as a player in 1992.
Split into simpler sentences: He remained at Upton Park until 1990, a year after West Ham were relegated to the Second Division. He and then signed for Watford, where he played for two years before retiring as a player in 1992.