Should you find yourself wanting to start over, simply uninstalling and reinstalling the game should put you back to the tutorial once you open the game again. Keep in mind that if you want to retain your previous progress at any time, ensure that you have that progress linked to an email address (through the settings) and properly verified it by clicking on the confirmation link sent to the email address you linked. Don't forget to also link your new progress to a different email address to not lose any progress.
If reinstalling doesn't address this, you can always reach out to our dedicated support by going through the in-game settings > My Support Tickets.