Three cleaning methods.

1. Take a boat from Treasure Island to Mysterious Island (the city of the sky), and then take a boat to Ariante (the desert).

2. Press the W key and then press the ESC key to see the world map. Click on the desert and send it to the desert for free.

3, with teleportation stone, bought by the store.

PS: If you are not in Treasure Island, you will still take a boat to Mystery Island, and then sit in Ariante. If you use methods 2 and 3, you don't have to look at it.