Unbind spectres

hi all,
how do u unbind your spectre gem if u change opinion about one mob and want capture another monster with the same gem?
i explain better.... i will never be so lucky to drop a second perfect socket orb (to do a 6L link) or i will never have so many currency to buy a perfect socket orb.
i remember i read something about this possibility in any preview patch notes... but i tried and i can't be able to do this.
thanks all
:)