Why does the Google OAuth screen say the Cronofy will be able to 'Permanently delete calendars'?
Cronofy requires full calendar access for some operations, such as creating calendars and setting the URL of an event.
This requires the full-access calendar scope, and this scope also includes the ability to delete calendars.
However, Cronofy does not support any way of deleting calendars - we do not have any code which can delete a calendar, despite it being mentioned in the scope description.