Source : Webster's Revised Unabridged Dictionary (1913)

Disabuse \Dis`a*buse"\, v. t. [imp. & p. p. {Disabused}; p. pr.
   & vb. n. {Disabusing}.] [Pref. dis- + abuse; cf. F.
   d['e]sabuser.]
   To set free from mistakes; to undeceive; to disengage from
   fallacy or deception; to set right.

         To undeceive and disabuse the people.    --South.

         If men are now sufficiently enlightened to disabuse
         themselves or artifice, hypocrisy, and superstition,
         they will consider this event as an era in their
         history.                                 --J. Adams.

Source : WordNet®

disabuse
     v : free somebody (from an erroneous belief)