The Firefox UI provides two operations that one could reasonably expect to clear stuff from the Web Storage and IndexedDB stores, but neither of them seems to do that (or anything else for that matter). Method 1: STR: In Preferences > Privacy > Site Data > Settings, pick a website and hit "Remove Selected". Expected results: The corresponding data is removed from [ProfileDir]/storage/* and webappsstore.sqlite. Actual results: The site disappears from the list, but nothing else seems to happen. Upon closing and reopening the Settings modal the site is back in the list. Method 2: STR: In the Clear History dialog, pick "Everything" as the time range and "Offline Website Data" as the data to be removed. Expected results: The corresponding data is removed from [ProfileDir]/storage/* and webappsstore.sqlite. Actual results: Nothing at all seems to happen. Firefox version: Nightly 55.0a1 (2017-05-23) (64-bit) Related: Bug 1047098 covers the specific case of "Clear History" not removing stuff from the [ProfileDir]/storage directory. Bug 527667 suggests clearing Web Storage via "Clear History" is tied to the "Cookies" selection. If that is so, then the meaning of "Offline Website Data" is a complete mystery and should probably be clarified somehow.

This is probably going to end up as duplicate of bug 1047098.

Keyword in last comment automatically closed this bug as duplicate. Leaving this open for the connection to the Preferences dialog. There may already be a bug for that, too.

bug 832660. bug 1047098.

For Method 1, did you click "Save Changes"? Method 2 is a dupe of bug 1047098.

(In reply to Johann Hofmann [:johannh] from comment #4) > For Method 1, did you click "Save Changes"? Wow. I seem to have overlooked this. The "Site Data" dialog does succeed in removing a website's data from (1) Web Storage, (2) IndexedDB, and (3) the cookie database. But see bug 1427234.