If you have a compressor, I highly recommend using an air chisel/hammer. I used it to remove the tile in our Laundry room, and most recently our master bath. Im using the cheap Cambell Hausfeld one that came with my compressor that I bought about 18 years ago. This is really the only time that I used it. If you don't have one, you can grab one for cheap at Harbor Freight. It even worked well for getting the tilebacker board up. It would inch itself under the board and I could use a prybar to break it free from the screws. Heres a crappy picture half way through the process.