Where in the bible does it say you can cast out someone and humiliate someone?

A member from the Church of Christ (Iglesia ni Cristo based in the Philippines) was expelled out of the church. In the process of expulsion, the church authority announce in a letter sent to all the churches around the whole stating there were not allowed in the church or in any activities related to the church. Where in the bible shows relation to this situation? Where does it say in the bible that you can do this? Where does it say that a church can send a letter stating that a man and his family is expelled?