Make sure that Firefox gets installed properly. Open the Firefox disk image (DMG) file with a double-click if necessary and drag the Firefox program to the application folder on your hard drive. You shouldn't double-click the Firefox application to run it from the disk image, but drag it out of the DMG folder instead. See: * https://support.mozilla.com/kb/Installing+Firefox+on+Mac * http://kb.mozillazine.org/Installing_Firefox#Mac_OS_X

Or simply right click on icon and select delete.