Source : Webster's Revised Unabridged Dictionary (1913)

Unspell \Un*spell"\, v. t. [1st pref. un- + spell.]
   To break the power of (a spell); to release (a person) from
   the influence of a spell; to disenchant. [R.]

         Such practices as these, . . . The more judicious
         Israelites unspelled.                    --Dryden.

Source : WordNet®

unspell
     v : release from a spell [ant: {spell}]