Sources have confirmed to Radio-Canada that Parent "was forced" to leave the union yesterday.
That was after a meeting with his executive committee.
Parent was re-elected as president of the union in 2012 with a three-year mandate.
He was planning to take his retirement at the end of the year.
For now, union vice-president Gaétan Simard will act as interim president until the next election.
Neither Michel Parent nor the union returned interview requests from CBC.