Delete a frontend and release the ports on which it listens.
shutdown frontend command is a drastic action. It deletes the frontend from the load balancer, releasing any ports it was bound to and removing it from the Stats page. Use this when no other option will suffice to free up the ports.
Below, we delete the frontend fe_main:
$ echo "shutdown frontend fe_main" | sudo socat stdio /var/run/hapee-2.1/hapee-lb.sock