To open the hole, I cut little slits outward from the hole, making little "reverse flower petals". If the petals are thin enough, then just take a tiny screwdriver and bend the petals outwards, and they will crack and break off. Just make sure to only use the very tip of the exacto or utility knife to make sure and not scratch the lens.
I can draw a picture later if that doesn't make sense.
I always take a sharp knife and just cut the plastic out with tip of the knife, it's move similar to peeling potato. It takes about 20 seconds to do that, I don't get whats the problem
I use a pair of micro pliers with really tiny tips, grab onto the plastic and just literally peel the plastic out like peeling an orange. It removes the plastic but still leaves the nut in place.