What is the way to remove the filthy religious teacher from the school, knowing that he has connections that protect him from dismissal, and he has committed shameful acts with some of the boys?

If it is confirmed that the teacher is committing indecency with students, then the official authorities must be informed. This falls under the category of denouncing evil. If verifying this depends on spying on him, then there is no blame, for apprehending thieves and highwaymen requires spying and tracking information. And whoever is certain of the existence of an evil deed, even if he has not witnessed it, is like one who has witnessed it; therefore, he must expose it and reveal what is hidden.