You need Synchronized objects and associate the objects with the peers.
When the peer disconnects from the host/room, the host automatically destroys the objects, which in turn destroys the objects on the other peers.
Adding a touch event on the host side, to destroy a player associated object will destroy the given object on the peers as well.
But the other way around will fail:
Adding the touch event on a peer (not host) to destroy any of the player objects ... the object in question would simply be recreated.
You can however, from the peer end, send a message to the host, with a reference to the object you want to destroy, and have the host destroy the object for the peer.