TripSpeak works without an account. Your progress is stored only on your phone; uninstalling the app deletes it.
If you turned on cloud backup, an account (anonymous or Google) and a copy of your progress are stored in Google Cloud Firestore. To delete both:
The backup and the account are deleted immediately. Progress on your device stays.
E-mail contact@bytelunalabs.com from (or mentioning) the Google account you used. We delete the account and backup within 30 days and confirm by e-mail.
Analytics and crash data (without your name or lesson content) are kept by Firebase for its standard retention period. Purchase records are kept by Google Play and RevenueCat as required for purchases, taxes and refunds.