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I don't have an answer but I am curious if anyone knows the answer. I poked around quite a bit on the browser and the best solution that I got to was use the back button to get back to the original webpage (homepage or page prior to objectionable content) then navigating forward (omitting objectionable content). Once you do that you can no longer access the previous page due to the back and forward button no longer registering it.
This doesn't fix the caching of the URL though so if you directly navigated to using the URL it will still pop up (i.e. start typing http://www.g it will automatically show google in the auto complete section).
Either way I could not find a history like function in the browser so while you may not be able to clear it no one can go to it directly (other than URL completion mentioned above)