The Greek New Testament Study App collects no data from the user and shares no data with anyone else. Unless you choose to backup your data using the built-in Backup/Synchronize function, your data files exist on your device alone.
If you do choose to use the backup function, however, then an encrypted copy of your data is stored on the backup server using a password stored only on your device and known only to you. Since the data itself is encrypted, no one (including me) can ever access it without your password. If you lose your password, you will have to create a new backup with a new password.
You can always delete your backup files in the program. But if you have any trouble with deleting your data, please contact me at software@claypotfrog.com, and I can manually delete your backup. (I cannot access your data; it's encrypted and only you have the password. But as the administrator of the backup accounts, I can delete your files off the backup server.)