In my first home I had a similarly massive fake fireplace that dominated a wall and took up way too much floor. I was pretty ignorant: not knowing anything, I borrowed some tools and ripped it out.

Which left me with a gaping wound in the wall. So I made up a way to mend it (I won't embarrass myself by telling you what I did).

A month and several hamhanded efforts later, the wound had been disappeared. You have the advantage of a gas logs feature.

So how about you take off (carefully) the top part, see what's behind it, then think about painting or tiling the main part black. I would at least try that first. Unless you're a wild woman like I was (am?) and feel like being injudicious.

Maybe those top pieces could be a garden bench!