It can be done on Humane, as that's how I got it
Use a sharp weapon, like a knife or machete. Try and take off the two arms first. Once both are gone, aim for the head and swing down at it. If using a knife, try stabbing the head, this caused it to explode most of the time for me.
Try to refrain from swinging wildly at it, as that will just cause more damage and kill it before you want to.