Please note: I did find this very similar question but believe ours is different since its unclear how far beneath the hardwood flooring the hearth goes.
Here is our current fireplace with a concrete hearth consisting of big ugly (our opinion) bluish and reddish stones:

I want to tear out just the "hearth" (the stone on the floor) and replace it with some more modern stone (e.g., give it a more modern look).
As far as tearing it out, any recommended approaches other than just breaking it up with a sledge hammer? I guess I'm wondering if hearths are typically glued or fastened to subflooring (or underlayment?) and what headaches I might run into trying to tear it out. Any ideas or is this super simple smash and trash?