To start a new game, you can simply change the server:

1. In the game settings, go to the section with the name of your current game server. Tap the button "Change".
2. In the list of servers, select a new server and tap the "Change" button at the bottom of the screen
3. You will receive a warning that switching to a new server will start the game over. Tap "Yes".

Note that your progress on the chosen server will be saved, and you will be able to come back whenever you want.

If you want to completely delete your progress on the selected server, please contact support.