There are 2 freeze plugs on that side (manifold side) of the engine block. This isn't one of those, however. I've not actually seen this before...which I find odd. There are 2 freeze plugs on the manifold side of the block (which I can see) and there is a freeze plug on the back side of the engine (something like 1 7/8 inches in diameter as I recall). This rear (back side) plug when removed will indeed help you clean out some of the gunk at the back of #6 cylinder. Drill a small hole in it, thread a screw in and pry it out using a claw hammer.
As for this plug, you could heat this up and probably remove it.
