There are several ways to protect your island.
- Firstly, I would recommend to not invite any players to your party unless you trust them.
- Control what your party members can/can't do on your island in the island menu (/is).
- Players will not take damage or lose hunger on another player's island.
- Players or mobs can't trample crops.
- Place a sign on a chest to lock it so no other players can open it.
- /kickplayers - This command will kick all non-party members from your island. Useful if players are getting in the way and you want to kick them off before locking your island, disabling your warp, or banning them.