This is for iOS only.
As of 26th May 2022, the team implemented a delete button, as shown below in the settings:
This was implemented as per EU GDPR regulation and this is a requirement for us to stay on the App Store. Once you've requested to delete your account, the delete process will begin.
From here you will be greeted by a screen upon each login with the following text.
You are unable to play because you requested that this account be deleted. Your account will be deleted 14 days after you made the request. Please contact Customer Support to restore your account if you have changed your mind.
To cancel the deletion, you can reach out to our support team by tapping on the "Contact Support" button or by emailing email@example.com
If you do not contact us within that 14-day period, we will delete your account. We can't recover this.