If you don't already have an account, and you're looking to get started and create one, all you need to do is head to the game's homepage and enter your desired username, password and email address in the registration fields displayed in the centre of the screen.
If you prefer, you can also click or tap on the Google or Apple icons to create your account via one of these services.
If you already have an account, and, for any reason, would like to start all over again, you must first head to your Account Settings and select 'Delete Account.' After the 48 hour timer expires, your account will be deleted and you'll be free to create a new one via the usual method.
I hope this helps, and as always, I wish you luck on the battlefield.