The Collaborative International Dictionary of English v.0.48:

Unsolder \Un*sol"der\, v. t. [1st pref. un- + solder.]
   To separate or disunite, as what has been soldered; hence, to
   divide; to sunder. [Formerly written also unsoder.]
   --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unsolder
    v 1: remove the soldering from