This question asks how to delete all Firefox cookies and cache, but I need to delete cookies from a specific site. How do I do it?
You can use
sqlite3 to delete cookies from terminal (Install if necessary:
sudo apt install sqlite3)
sqlite3 ~/.mozilla/firefox/*.default/cookies.sqlite \ 'delete from moz_cookies where baseDomain="example.com";'
sqlite3 ~/.mozilla/firefox/*.default/cookies.sqlite \ 'delete from moz_cookies where baseDomain LIKE "%google.%";'
To delete history for a specific site:
sqlite3 ~/.mozilla/firefox/*.default/places.sqlite \ ' delete from moz_historyvisits where place_id in (select h.place_id from moz_historyvisits h join moz_places p on h.place_id = p.id where p.url like "%example.com/%"); delete from moz_places where url like "%example.com/%"; '
There are some more interesting tables and you might need to delete from e.g.
moz_bookmarks_deleted to remove more trails from a domain.
Note: Firefox must be closed, or you will see an error message:
Error: database is locked
To save energy and time, you could install an add-on for this. Then you dont need to clear the cache of cookies manually any more. In FF browser go to menu in right corner above. Select "add-ons" and type as search word there above "cookie blocker" - so you have the free choice for data-protection of your privacy. There you can install for example "Ghostery" as add-on, then adjust it to your needs.
Here's a quick and handy method I use often:
Bookmarklet source: https://www.squarefree.com/bookmarklets/zap.html