Small amounts of user data "values in the textfield" is stored in the App and is directly attached to the app and stored locally on your device. Which are also deleted when the app is deleted.
To delete the last bits stored in the app. You can uninstall the app or delete the app in the "Settings" tab.
To see how Apple handles your data you should read their policies.
All devices shown are trademark of Apple Inc., registered in the U.S. and other countries.
For further information about the app and how it handles your personal data you can contact me at email@example.com