How do I start a new game in Pokemon Sun/Moon?
Solution 1:
You first need to delete your existing saved game.
To delete a save game, hold UP + B + X in the title screen (the screen with Solgaleo or Lunala). This will also give you the option to re-pick the language setting of the game after you delete your save.
After you delete your save, you will be able to start a new game.