The Collaborative International Dictionary of English v.0.48:

Deconsecrate \De*con"se*crate\ (d[-e]*k[o^]n"s[-e]*kr[=a]t), v.
   t.
   To deprive of sacredness; to secularize. --
   De*con`se*cra"tion, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

deconsecrate
    v 1: remove the consecration from a person or an object [syn:
         desecrate, unhallow, deconsecrate] [ant: bless,
         consecrate, hallow, sanctify]