Source : Webster's Revised Unabridged Dictionary (1913)

Unpick \Un*pick\, v. t. [1st pref. un- (intensive) + pick.]
   To pick out; to undo by picking.

Source : WordNet®

unpick
     v 1: become or cause to become undone by separating the fibers or
          threads of; "the sweater unravelled" [syn: {unravel}, {unknot},
           {unscramble}, {untangle}] [ant: {ravel}, {ravel}]
     2: undo (the stitches) of (a piece of sewing)