How to modify a M-84D Meling standard oil pump?

I'm about to take an emery cloth to the sharp edges in side the pump.

Question - I would like to take the spring and plunger out for cleaning and inspection. I notice that the end of the hole
is capped off with what looks like a freeze plug (see photo above). How do I get this out? Can I get it out without damaging it? Can I put it back in?
Or do I need to get another new plug?

Bob
Tucson