code: public void revokeMembership(Collection<? extends Jid> jids) throws XMPPErrorException, NoResponseException, NotConnectedException, InterruptedException {
          changeAffiliationByAdmin(jids, MUCAffiliation.none);
      }
docs: Revokes users' membership. Only administrators are able to revoke membership. A user
  that becomes a room member will be able to enter a room of type Members-Only (i.e. a room
  that a user cannot enter without being on the member list). If the user is in the room and
  the room is of type members-only then the user will be removed from the room.
  
  @param jids the bare XMPP user IDs of the users to revoke membership.
  @throws XMPPErrorException if an error occurs revoking membership to a user.
  @throws NoResponseException if there was no response from the server.
  @throws NotConnectedException
  @throws InterruptedException