code: function destroy(released) {
      function flush() {
        if (messages.messages.length && !released) {
          return messages.flush();
        }
        return Promise.resolve();
      }
  
      function finalize() {
        messages.ignoreSignal();
        channel.destroy();
        channel = undefined;
      }
  
      return flush().then(function(){
        return unsubscribe(channel, options);
      }).then(finalize, finalize);
    }
docs: Destroy the queue
  
  @public