A sledgehammer is very effective. For a more delicate removal, you can pry it off with a pry bar. Be careful of electricity and any pipes. Otherwise, it's like peeling an onion, removing a layer at a time. Close off the area as there will be dust.
Sledge hammer. Tile scraper. Hammer and chisel. Wear hand and eye protection. Dry wall patching compound for wall repairs.
Thank you so much for yr answers. Do you think a pry bar would work on these very old tiles? Sledgehammer sounds good too - scary and exciting for someone who's barely used a hammer...