Firefox instructions here or: In order to find privacy settings in Firefox, in the menu, select History, then select Clear Recent History… and select the Follow the menu options or search for privacy. Make sure to be thorough and understand how to clear:
Want to save time the next time you visit (after you’ve cleared your data)? Make sure to use Private Browsing: this option prevents Firefox from installing cookies and doesn’t keep the history or cache data. This option can be found under File in the menu.