Complex sentence: Chandler retired from the position of publisher in 1980 at the age of 52 to become chairman of Times Mirror, reducing his involvement in the day-to-day operations of the company.
Split into simpler sentences: Chandler retired from the position of publisher in 1980 at the age of 52. In 1980, he stepped down as publisher and became chairman of Times Mirror, reducing his involvement in the day-to-day operations of the company.