The Viewpark club survived relegation from the Super League First Division on the last day of the season, but financial constraints have seen a restructuring within the club.
A club statement said: “It is with deep regret that following a restructuring review Thorniewood United have to announce the departure of manager Kieran McGuinness and assistant Martin Devlin.
“The club would like to thank them both for their hard work and tireless efforts which have kept us in the Super League First Division during their time in charge of the football team.
“Since their inception the Thorniewood United Juniors Social Club, as per their constitution, have contributed towards the upkeep of the football team.
“Regrettably, due to their own financial restraints at this time, the social club have not been able to do this over the past few years and as such the football committee have had to restructure the footballing set up to ensure the continued viability of the team.
“The committee have appointed ex-Thorniewood player Andrew Frame as their new manager and he comes to us with a highly successful record managing local amateur side Whitefield Rovers.
“Andy is looking forward to the challenge of his first season as a manager in the highly competitive Super League First Division.”