The Collaborative International Dictionary of English v.0.48:

Devulgarize \De*vul"gar*ize\, v. t.
   To free from what is vulgar, common, or narrow.
   [1913 Webster]

         Shakespeare and Plutarch's "Lives" are very
         devulgarizing books.                     --E. A.
                                                  Abbott.
   [1913 Webster]