1. Click on the History tab in the menu bar..

2. In the drop down menu which appears click on “Clear recent history”.

3. In the window that opens there is a drop down menu at the top called “Time range to clear”. Click on the arrow to open the down menu and choose “Clear everything”. The default values of what to clear in the window below should normally be ok.

Remark: This operation doesn't carry any risk to your data.