Regan Nickels, who now serves as assistant superintendent for business and operations, will become superintendent on July 1 of next year.
Lyons, who was hired in 1992, first retired in 2015 but was hired back a month later and given a five-year contract that expires in 2020.
"Next year will be my fifth year, which will be my final year now that the board has endorsed Mrs. Nichols as our new superintendent of schools, effective July 1, 2020. That will dovetail perfectly with my retirement on June 30, 2020" Lyons said.
Lyons said Nickels has been with the district for 14 years, serving as principal at both Reeds Brook Middle School and George B. Weatherbee School.