code: public synchronized void destroyForPort(int port)
     {
        synchronized(portMap)
        {
           UndertowServerEngine ref = portMap.remove(port);
           if (ref != null)
           {
              if (LOG.isDebugEnabled())
              {
                 LOG.debug("Stopping HttpServer Engine on port " + port + ".");
              }
              try
              {
                 ref.stop();
              }
              catch (Exception e)
              {
                 LOG.warn("", e);
              }
           }
        }
     }
docs: This method removes the Server Engine from the port map and stops it.