The Collaborative International Dictionary of English v.0.48:

Disorganize \Dis*or"gan*ize\, v. t. [imp. & p. p.
   Disorganized; p. pr. & vb. n. Disorganizing.] [Pref. dis-
   + organize: cf. F. d['e]sorganiser.]
   To destroy the organic structure or regular system of (a
   government, a society, a party, etc.); to break up (what is
   organized); to throw into utter disorder; to disarrange.
   [1913 Webster]

         Lyford . . . attempted to disorganize the church.
                                                  --Eliot
                                                  (1809).
   [1913 Webster]

WordNet (r) 3.0 (2006):

disorganize
    v 1: remove the organization from [syn: disorganize,
         disorganise] [ant: organise, organize]