I don't know of anyway to turn off just History.
If you go into Settings > Safari, you can activate Private Browsing. This will prevent History, but it also stops Safari from accepting cookies. Some sites do not operate correctly if you can't accept cookies. The normal setting for this is From Visited.
If you only need private browsing some of the time, you could get a third party browser that supports private browsing and use it as the occasion demands. Atomic is a cheap browser with a privacy mode. There are lots of other choices. The new Chrome is getting great reviews, it's free, and has the ability to browse private (incognito) per tab. I've got to remember to download it an play around with it some day soon.