How can one deal with a father who frequents Zawāyā (Sufi lodges) and seeks blessings from graves, becomes angry when advised, believes in the righteousness of dervishes and asks them for prayers, often curses and swears at religion when angry, and asks his son to shave his beard or trim it?

You must continue to advise your father kindly and explain the truth to him with evidence from the Qur'an and Sunnah, and warn him against innovations (bid'ah), sins, and polytheism (shirk), while choosing appropriate times for this and avoiding angering him. Seek help from righteous people whose advice your father might accept. Do not obey him except in what is good. Therefore, do not respond to his command to shave your beard. Trimming it if it exceeds a fistful is a matter of scholarly disagreement.