Doccument created by Guest in webform can't be deleted


I created webform for a custom doctype. It can be saved successfully.
But then they can’t be deleted and in the browser console said:

[Error] Unhandled Promise Rejection: NotAllowedError: The request is not allowed by the user agent or the platform in the current context, possibly because the user denied permission.

And from the history at the bottom I see the creator is Guest, so:

  1. I can’t login as Guest and go to desk (not allowed by frappe).
  2. How to delete the docs while login as others (including Administrator)?
  3. What is the proper way to allow permission for the docs or to change the creator to someone else (with System Manager role)?

Thank you