Yes, how exactly do they do that? By quitting?

No, by going public and protesting against him. Even when the guy who was removed came out publicly after his players spoke out against him, he was still credible enough. Imagine what it would have looked like if the players also protested along with it. Things would have moved so quickly. What do you think he would do, fire them all right before Worlds? That would look even worse, and what he did was already enough for them to get rid of him.

So in short, yeah the players could have started this process much sooner if they were brave enough to stand up. They were in a strong position since the team is nothing without them.