Blocking messages from openfire server

Hello boys, I have a questions, I´m building a client with smack api and I´m using the openfire server. I create a room for the user can send messages, but when an user join to the room the server send automatically a message similar to this (this room isn´t anonimo or the subject have been changed to free) and i don´t want show this messages my questions is How Can I delete this messages or blocking for the users cant recieve there some method in smack api for blocking this messages, I am use pollmessages for recieve the messages that the server send to every user that connect to the room.

Thank Heider