Source : Webster's Revised Unabridged Dictionary (1913)

Unstring \Un*string"\, v. t. [1st pref. un- + string.]
   1. To deprive of a string or strings; also, to take from a
      string; as, to unstring beads.

   2. To loosen the string or strings of; as, to unstring a harp
      or a bow.

   3. To relax the tension of; to loosen. ``His garland they
      unstring.'' --Dryden. Used also figuratively; as, his
      nerves were unstrung by fear.

Source : WordNet®

unstring
     v : remove the strings from; "unstring my guitar" [ant: {string}]
     [also: {unstrung}]