If you decide to delete your account, you have to:
1. Open the "Google Play Games" app and tap the "Settings".
2. Find and tap the "Delete Play Games account & data".
3. Find the game "Balls Breaker" and tap "Delete" button.
4. Tap "Permanently delete" button.
Note: If you delete your account, you will delete all the data and progress. You can delete your account only if you are a registered user.