See: *http://kb.mozillazine.org/Uninstalling_add-ons *http://kb.mozillazine.org/Uninstalling_toolbars Extensions that do not have a "Remove" button are installed by other software and are not under control of the Firefox extension manager.<br /> Such globally installed extensions are usually found via a registry scan or are installed in a location that Firefox scans for installed extensions. * https://developer.mozilla.org/en/Adding_Extensions_using_the_Windows_Registry Extensions installed this way need to be removed via the settings (options/preferences) of the program that has added this extension or you need to uninstall this program via "Control Panel > Programs".<br /> In Firefox you an only disable such an extension.