Bully in Management

Hi
We have a person in our league management who is manipulating and controlling and spoiling roller derby for everyone. I read Q's article on bad girls and it's like she was describing our meanie to the T. The league is slowly starting to see through her and she doesn't have a lot of friends left. She's super friendly with every new batch of freshies coming in. Even though she's not the only manager, she's so overpowering and manipulative that she basically controls the whole league and makes all the decisions without consulting any one else. When she announces these decisions it was always "we" decided... Anyway. I'm not sure how to go about changing it because she's made herself indispensable and although everybody knows that she cannot be trusted, very few believe that we'll be able to manage without her. Quite a few people have left the league and our inter-league relations are also suffering. I can go on mentioning examples of everything she's done, but I really just want people's thoughts on what the way forward will be. We don't have a grievance council, but as far as I know it's in the pipeline - maybe that would be the avenue?