Along with manager Daryl McMahon, the pair played a huge part in the club's run to the play-offs last season.
The club say the move is part of a 'financial restructure at the club'.
Fleet chairman Dean Pooley told the club's website that the decision wasn't taken lightly.
“I’ve seen up close how dedicated and hard-working they have been in all their years with this football club. That, of course, makes our decision to part ways even harder on a personal level.
“I can’t thank them enough for their input in my time here. They can be justifiably proud of our promotion and play-off qualification over the past two seasons and this club has consistently improved year on year since 2015 right up to last season’s sixth place.
"They depart with all of this football club’s warmest wishes for the future.”
Manager Daryl McMahon added: “I’m very sad to have to lose them. They’ve been terrific for the football club and me as a player working under them. Then as my assistant and first-team coach for three years where we went through three play-off campaigns together in a row.
"To lose them now is a blow and I simply can do no more right this minute than thank them sincerely and wish them all the best for the future.”