stackauth.com has used some local storage which my Safari does not show me, and hence cannot be deleted. So, in general: how to ensure all local storage is deleted from Safari?
Some background and details:
The HTML5 Local Storage allows websites to store information on a computer. (That's a bit like cookies, but the contents are not sent to the server automatically.) Like when one has once logged in to the (new) Twitter website, then when viewing that site and pasting the following into the location bar shows a lot of details, even when not currently logged in†:
To get rid of this data: in Google Chrome "Delete cookies and other site data" does the trick. In Firefox, it's deleted whenever cookies are deleted. Not so much in Safari.
In Safari there seems to be a related preference in Security, button "Show databases". However: that list of "Show databases" in Safari does NOT mention stackauth.com, as used by the Stack Exchange global network auto-login. And after using "Remove all", I still get results on that site:
I could delete this by using
(I'm on a Mac, using the latest Safari on the latest OS X.)
† When the popup is too large to see any close button, then hit Esc or Return to close the alert dialog.