Spitfires owner and president Steve Riolo made the announcement after Windsor's 4-3 loss to the Peterborough Petes on Friday night.
In a statement, Riolo said Mantha's deal was terminated after a review of the terms of his contract revealed a number of incidents the club thought was detrimental to the players of the team.
Riolo also indicated there would be no financial compensation for Mantha, who was in the first year of a three-year contract.
On Oct. 18, the Ontario Hockey League handed Mantha a one-year suspension as general manager and 25 games as coach for a hazing incident involving several of his players.
Mantha received an additional 15-game suspension as coach for a fight involving players Akim Aliu and Steve Downie during a Sept. 28 team practice.
The Spitfires were also fined $35,000.
The alleged hazing incident occurred following a Sept. 9 pre-season game when the league claims rookie players were told to strip and made to stand naked inside a small bathroom at the back of the team bus.
Mantha sat across from Riolo on the team bus when the incident took place. Both said they had no knowledge of the incident.
Mantha was not on the ice when the altercation between Aliu and Downie occurred.
with files from the Windsor Star