Dehaze option is only available with Lightroom CC 2015.
In order to use this, you need to get a subscription for Lightroom CC 2015.
Hope this helps.
why is it not available as a update for the non cc versions ?
Traditionally, functionality updates have come with the next whole-number version upgrade, in this case it would be LR 7, assuming there will be a LR 7 after LR 6, with the .x version updates only having bug-fixes and new camera support.
With CC you pay a little all the time and you get features as they are added. This is one benefit of CC, continuous updates, with continuous payments, along with getting Photoshop as part of the deal.
With LR numbered versions (i.e. 5, 6, 7) you pay more, one time, and get more features, one time.
The update was added after version 6.0 was released. For the non-CC users, any new features will be available in version 7.0.