I bought new tiles to replace the old tiles in front of my fireplace, which is on floor level. The new tiles are thicker than the old tiles, so that the wood floor is not as high as the tiles, making it impossible to grout along the edge with the wood floor. Should I break up the concrete slab that already exists to lower the area where the tile goes? And if so, what is the best way to do this without damaging the wood subfloor? Thanks for your help.

Breaking up the slab is way more work than most home owners would tackle. How would it look if you bought or made a thin Oak beveled strip to create a transition up to the tile. A bit like going fom tile to carpet.

Here's my suggestion. Use quarter round molding in front of your tile and the floor where they meet up or some kind of wood piece. It will look like it has always been there. Please do not tear up the tile. There are all kinds of sizes and designs in molding take your pick and makeit as you like. Staining the wood to match your floors or color stain even. So much easier and much better looking. Beccie