It's your non-door! Do what you like.

>non-open-able door

People in this thread seem to be missing this. A non-openable door is not a door. I assume it's made of wood. If so, drill away.

Suggestions:

1. Use a spade bit so that a bit of pokey-ness of the drill comes out the other side before the hole is cleared. Then switch sides and drill back in, which reduces tear-out.

2. get a piece of closed cell foam (you can check by trying to blow through it, no air going through means it's closed cell, a pool noodle or a foam mat would work), and use that for your plug, just cut with scissors. Hot-glue them together to make it as thick as your door. If you want to make it pretty, glue a circular piece of wood to this foam plug. Make the foam plug slightly larger than the hole.