Appointed in January 2015 as the successor to Graham Kemp after switching from Poole Town with his number two Nick Crittenden, the the Magpies announced the duo's departure over the weekend after their 3-3 draw with King's Lynn Town at The Walks on Saturday.
In a statement on their website inviting potential successors to contact chairman Matt Lucas, the Magpies confirmed the pair were standing down after the club's Boxing Day clash at home to Weymouth in the EVO-STIK League Southern's top flight.
Jermyn, pictured, spent 14 seasons at the Dorset club turning out in midfield and defence and the Magpies paid a warm tribute to the 35-year-old and his assistant in the statement expressing their regret at their decision to leave.
A spokesman said: "It is with the utmost sadness that the board of directors of Dorchester Town FC announce the resignation of Mark Jermyn as manager of the club. Mark's last match in charge will be the home Southern League game against Weymouth on Boxing Day. The board respects Mark’s decision and totally understands his reasons.
"Since he made his debut as a player against Worcester City on 8 October 2000, Mark has represented the club with distinction. Reaching 700 appearances is a feat that very few players will achieve in this day and age.
"He has always been a winner and will be remembered for his leadership, courage and determination, on numerous occasions playing on whilst in considerable pain for the benefit of the team. His entire playing career has been dedicated to Dorchester Town FC.
"Upon returning to the club two years ago, as player manager Mark lead from the front installing energy and enthusiasm lifting a relegation threatened team into a position of safety. The club wishes Mark, Carly, Jasper and Hugo all the best for the future.
"Nick Crittenden has also confirmed he will be leaving the club at the same time, and the board would like to thank him for his service over the years both as a player and in a coaching capacity."
The club added: "The recruitment process for a successor will start immediately and prospective applicants should contact the club chairman Matt Lucas at: chairman@dorchestertownfc.com."
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