The club issued a statement revealing that their manager of six seasons had seriously overspent his allocated budget over the first half of the club's inaugural season in Southern League.
Despite repeated warnings to him in recent months, the spending hasn't been curtailed and the club felt that they had no option but to seek his resignation at a recent meeting.
Despite the overspend. the club's form has dipped alarmingly during December and Fisher's side have only picked up two points out of a possible 18 to drop to fourteenth in the table, despite a promising start.
Club chairman Ollie Croft said: “We could not allow this to go on, otherwise the club would be in serious financial difficulties.
“Adam has done very well for the club on the field in his time here, but at too high a price.
“We know you need a competitive budget to complete in the Southern League football, but you don't need to be frivolous with money.”
Fisher issued his own statement, saying: “It is with real sadness, regret and disappointment that I have resigned from my position as manager.
“Unfortunately, I feel I have been left with no choice due to budgeting issues and myself and the club have completely different ambitions and views moving forward and I feel now is 100% the right time to leave.
“This is nothing to do with current results as myself and the football committee were completely confident we could turn things around.
“It`s been an incredible six years that include two league titles, two promotions and five cup finals, two of which we won.
“But more importantly, getting the club promoted to Step 4 for the first time in their 98-year history was something I am proud of, whilst developing a fantastic support base and great community spirit.”
Fisher, who has won two promotions in his half-dozen seasons at the BP Mitchell, leaves his post immediately.