I want to delete cache and cookies for a single login

Check this old link to see what you can do. https://support.mozilla.org/mk/questions/1378359 https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox

Clearing the cache is all or nothing, you can't clear the cache for a single origin (protocol and hostname). *https://support.mozilla.org/en-US/kb/how-clear-firefox-cache You can reload webpage(s) and bypass the cache to refresh possibly outdated or corrupted files. *hold down the Shift key and left-click the Reload button *press "Ctrl+F5" or press "Ctrl+Shift+R" (Windows,Linux) *press "Command+Shift+R" (Mac)