How do I clear my history?
Click the menu button 
on the upper right corner, choose , and then select History. Click on Clear Recent History.
Select how much history you want to clear:
- Click the drop-down menu next to Time range to clear to choose how much of your history Firefox will clear.
- Next, click the arrow next to Details to select exactly what information will get cleared. Your choices are described in the What things are included in my history? section above.
- Finally, click the button. The window will close and the items you've selected will be cleared.