Got It!!! Go To: Firefox/Tools/Options/Privacy/Tracking Checked box/Tell websites I do not want to be tracked/ History Firefox will: Never Remember History/ You may also want to: clear all current history/ Clear now/ click OK, ---> got it, that is your answer.<-- (Right click the left image below to open in a new tab) And it is my answer as well, as I was confounded with this problem for some time. Now after you do this close your Firefox browser, and open back up Firefox browser, and there will be maybe only one or two cookies, depending on your browsers' home page. I tried other methods to get rid of persistent cookies that would not delete by, CookieKiller, and TACO Targeted Advertising Cookie Opt-Out, those did not help, and I tried the methods listed on these links but they did not work:http://webdevwonders.com/clear-dom-storage/ Also this method did not work:http://justplainobvious.blogspot.com/2009/03/firefox-wont-delete-cookies.html Next to make your Firefox browsing possible, go to/Firefox/Tools/Options/Privacy/,Tracking Checked box/Tell websites I do not want to be tracked, History Firefox will: Use custom settings for history, unchecked box Always use private browsing mode, unchecked box Remember my browsing history, unchecked box Remember download history, unchecked box Remember search and form history, checked box Accept cookies from sites, checked box Accept third party cookies, Keep until: I close Firefox, checked box clear history when Firefox closes, /settings all nine boxes checked/ click --->OK! (Right click the right image below to open in a new tab) All Cookies are gone/history/deleted.