All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If what is mentioned about that man is proven to be true, then he should be advised and forbidden from committing these evils in compliance with the verse: {And let there be (arising) from you a nation inviting to (all that is) good, enjoining what is right and forbidding what is wrong, and those will be the successful.} [Quran 3:104]
Abu Sa‘eed Al-Khudri narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said, "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; and if he cannot, then with his heart (by at least hating it and believing that it is wrong), and that is the weakest of faith." [Muslim]
If he does not respond to the truth and persists in his evil practices, then people should be warned against him, and cooperation should be sought with the Islamic centers in that country to try to prevent him from such practices. Do not fear his cunning schemes or his followers; by regularly seeking refuge with Allaah night and day, and by reciting the reported Thikr (expressions of remembrance of Allaah), Allaah Almighty will safeguard you, with His permission, from their evil.
Allaah knows best.