Completely deleting app data...

The app provider said my account is corrupted and to create a new account. I deleted the app and confirmed warnings that all app data would be deleted. In settings, I confirmed there was no iCloud storage and no iPhone storage for the app. In the App Store, I chose apps not on this phone and hid the app to get rid of the cloud symbol next to it. I restarted the phone, downloaded the app and opened it. It still opened my corrupted account. Where is it storing my account data and how do I delete it?