Lightroom 6 does not have DeHaze - only Lightroom CC 2015 does.
DeHaze should be in the "standalone" release Lightroom 7 (whenever it comes) - until then, only Creative Cloud Lightroom users have deHaze.
Dehaze feature is only available to Lightroom CC 2015 version.
Below is the document for the same
But you would still be able to receive other updates for Lightroom 6 until we release the new version for Lightroom.
To raise a feature request for not having dehaze in standalone version, I would suggest you to raise a request at below provided link: