How to clear Firefox cache and cookies Open Firefox. The following is recommended: - Preserve Favorites website data (only if necessary to refresh the site in question) - Temporary Internet files and website files. Use the check boxes to select the items you'd like to clear from the list. Press the CTRL-Shift-Delete (Windows), Command-Shift-Delete (Mac). You can also remove cookies from all sites in the list in one go by clicking on Remove All, followed by Remove Now on the dialog box that appears.
Choose the site or sites that you want to delete cookies from, then click Remove. To clear cookies on Safari, go to Safari > Preferences > Privacy > Manage Website Data.
