1. Finish or discard any workout in progress, because deletion is blocked while a workout is active.
  2. Open Settings → Data → Delete All Data.
  3. Read the confirmation and tap Delete Everywhere.

This cannot be undone. If you might want the history later, export CSV or JSON first.

Because SetGrip has no account, there is nothing else to close: no profile to delete, no email to unsubscribe. Deleting the app afterwards removes the local database. The iCloud copy is already gone after the step above. If you only want the data off one device and not from iCloud, delete the app instead of using Delete All Data.