Google and Apple Account Deletion Requirements
Google and Apple require that applications listed through their respective App Stores must give any user who creates an account the option to delete the account. Whether you use an authentication method where you must manually register a user, such as email/password authentication, or one that that automatically creates a user, such as Sign-In with Apple, you must implement user account deletion.
Call the App.deleteUser() on a user object to delete the user's account from your App Services App. This deletes the account from the App on the server in addition to clearing local data.
final currentUser = app.currentUser!; await app.deleteUser(currentUser);
The user must sign up for a new account to use your App in the future. Even if the user signs up again with the same credentials, App Services creates a new user account with a new User ID.
Deleting a User Doesn't Delete User Metadata
Deleting a user only deletes the user object, which may contain associated metadata. This does not delete custom user data or user-entered data from your application. Google and Apple require that you disclose data retention and deletion policies to your application customers and give them a way to request user data deletion. If you collect additional user data, you must implement your own methods or processes to delete that data.