You can clear your history through safari or in 'Settings'. To do this via Safari tap the 'Book' icon in the top left hand corner. You will then see on the left hand side A list 2nd one down 'History' tap this then at the bottom press 'Clear'. You will then be given options of what you would like to clear. Or through Settings > Scroll down left hand side to Safari > Scroll down right hand side to Clear History & Web site data.
I do clear mine but only because I have an ipad2 that is almost 5 years old and I find it helps the performance.