Our boss just announced that Alex is no longer in charge of his team. In charge: Leading, responsible for. He fired him.
Our boss found/said that Alex is no longer in control of his team. He found/said that Alex is not able to control the behavior of the team during play.
If you are no longer in charge of a team, you no longer officially direct the operations of the team.
If you are no longer in control of a team, you are no longer able to direct the operations of the team – perhaps because no one is listening to your instructions; or perhaps because a more forceful character has usurped your authority.