Thanks very much J.A. That worked.Welcome to iPhone Forums, medskj!
Do you have Restrictions enabled?
If you go to Settings - General - Restrictions - (enter password) - Allowed Content - Websites, it's only possible to clear your history in Safari, if "All Websites" is checkmarked. With the other two options, this feature (Clear History and Website Data) will be greyed out in Settings - Safari, so you won't be able to use it.