Clearing Cache in Mozilla Firefox 1. In the Firefox window, click the menu button in the top right, then click Settings in the drop-down menu. 2. In the Settings menu, click the Privacy and Security tab, then click the Clear Data... button under the Cookies and Site Data heading. You may need to scroll down a bit to see the Cookies and Site Data heading. 3. Ensure both boxes are checked in the Clear Data window, and then click Clear.
