Is it permissible for me to disown my son and prevent him from coming home, because he is living with a non-Muslim girl outside of marriage, and he refuses advice and disobeys his parents?

It is permissible to boycott a disobedient son as a deterrent and a form of discipline, and there is no sin upon the parents in doing so if the boycott is for the purpose of rectification. It is recommended to strive diligently in reforming the son and not to despair, to seek assistance from righteous people to supplicate for him, and to persist in supplicating for his guidance. Furthermore, attention must be drawn to the dangers of residing in lands of disbelievers, concerning one's religion and morals.