Blow it up with a grenade. If you're right about this finch being a robot or a robofinch, it should explode, and you should be left with scrap metal which you can sell on Ebay. If it is just a finch, then it should still explode and you should be left with something that smells like fried chicken. Yum!
You had better make sure. Try to electricute it. If it is a robot, it will probably overload. If it is a finch, it will just die.