You can inspect and manage the permissions for all domains on the <b>about:permissions</b> page. *https://support.mozilla.org/kb/how-do-i-manage-website-permissions You can remove all stored data from a specific domain via "Forget About This Site" in the right-click context menu of an history entry (Show All History or History sidebar) or via the about:permissions page. Using "Forget About This Site" will remove everything like bookmarks, cookies, passwords, cache, history, and exceptions from that domain, so be cautious and if you have a password or other data from that domain that you do not want to lose then make a note of those passwords and bookmarks.<br /> You can't recover from that "forget" unless you have a backup of the affected files. It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.