Logged-in users who have already completed a form submission and later return to that form will, by default, be warned that they have already completed the form. The warning also contains a link which, when clicked, will show the user a listing of the previous submissions they have already completed.
This facility may be disabled when we have no concern around receiving multiple submissions from our logged-in users.
Uncheck the box at the Show the notification about previous submissions option under ADVANCED SETTINGS on the Form settings page.
Webform is configured to enable this option ...