code: public void removeListener(final ParticipantsListener participantsListener) {
          MessagingListener messagingListener = participantsListeners.get(participantsListener);
          if (messagingListener != null) {
              client.removeListener(messagingListener);
              participantsListeners.remove(participantsListener);
          }
      }
docs: Removes listener for changes in participant list in conversations.
  
  @param participantsListener Listener for changes in participant list in conversations.