How to clear your browsing history
In Safari 4, from the Safari menu select Edit > Reset Safari (PC users) or select Safari > Reset Safari (Mac users).
In Safari 5, from the toolbar select the Action (Gear) icon > Reset Safari.
A new warning window opens. Tick the types of history you want to delete and select Reset.
The browser restarts automatically.
Private Browsing
Safari also give the option of Private Browsing so that no history is recorded for a particular session.
To set this click on edit in the browser toolbar > select Private Browsing.
A confirmation screen of Private Browsing will appear - click OK to confirm you wish to turn on private browsing.
NB. Private Browsing isn't automatic and has to be turned on for each session.