How did the catholic church censor martin luther

They used excommunication which is basically blacklisting someone in the name of the church, which means that he's not allowed there anymore. They also made him say that his beliefs were false. The church did that so people wouldn't believe what he was saying, the church wanted people to only believe what they taught. 

hope this helps, ask if you have more questions or for clarification on anything. 

What he said