Some observations that might be useful.
Dining room wall with 9' x 5' mirrored with 12" square tiles. These were stuck onto painted drywall with glue tabs at each corner. Glue tabs are 1" square. Orange-ish color, still spongy in places. They kept the tiles 1/8" off the wall. Tiles are some kind of glass about 3/16" thick. The tiles have minor flex when pushed/pulled in the center. Look like every other glass tile wall I've seen, but that's all I know about glass tiles, so YMMV.
Wife wanted them gone since we moved in but I put her off for 13 years. Then I caved for a china cabinet, which has to go on that wall, which meant I had to cave on the tiles. I don't know for sure how long the tiles were on the wall, but from paint evidence I'd bet 30-35 years.
I spent an hour or so on the net and all the advice I saw there was basically hammer with glass shards all over the place. Really nothing that I found suitable.
Since I've done body work I thought I'd try a suction cup first. Went to O'Reilly's auto parts and bought a simple push on suction cup for $5. It's 5" diameter. My son was over and he pushed it on the center of a tile, turned his head away and jerked it straight back. Tile popped right out, taking the paint on all 4 tabs and the outer layer of paper. I told him to not do more because I wanted a tarp down. A few days ago I put the tarp down and went after the rest. Popped the lower 3 rows of 9 with no breakage, then I needed to use the ladder. Wife said to wait an hour, as son was coming over.
I should have known when he put the stepladder sideways to the wall. Still haven't learned he's just not as careful as me and it's best I keep a close eye on him. He lackadaisically jerked his first tile off center, and it broke into many pieces the biggest one jumping to his chest. Minor cut on his skin right through his shirt. Glass shards all over. This is vicious glass, hard and sharp slivers. Cleaned it all up and he backed out being glass-shy, so I did the rest with the ladder properly centered.
Had him brace my back while I popped them out. No breakage. That was the only one of 45 to break. Center the cup, and jerk straight back from the wall. Immediately grab the tile and slide the suction cup off. I dropped one tile on the tarp when it came off the cup because I held it too long with the cup. Lucky it didn't break when it fell. Watch the edges, they can cut. Though I didn't - because I'm sometimes stupid - it's best to wear heavy gloves.
Because I'm sometimes stupid with confidence, I just turned my head away when I jerked, but the safe way is to wear safety glasses with side guards, heavy clothing, etc, etc. Use all due precautions. This glass is baaaad. Now that I think about, I didn't take adequate safety precautions. You should be smarter.
There was a strip of 2" x 12" pieces butting the ceiling, cut from whole tiles, each with 2 of the same tabs. I wiggled a Purdy 2" putty knife through the tabs and those came off easy.
I've cleaned away loose paint from where the tabs pulled it from the wall and I'm going to run the orbital sander over all the tab spots to level them before I spackle. That's 45 x 4 or 180 spots. One spackle coat on the spots should do it, then easy sanding, but it'll take maybe 3 primer coats before a finish coat not to show through. We'll see. My other option is to slap 1/4" drywall over it, but I won't go there. I hate hanging drywall and there's a switch box to deal with. Rather canvas or good paper over it if the spackle doesn't work out. About 15 tabs stayed on the wall. About 15 tabs pulled a bit of the plaster beyond paper. Maybe half of those will want 2 spackle coats due to shrinkage.
Reason I'm writing this now is it's easier than finishing the wall. That's why I don't know how it will turn out. Now, assuming you have similar tiles, I'm going to recommend doing what I didn't do, and didn't realize as a method until I removed the top thin strips with the putty knife. Wish I had tried this, and it might work for you.
1. Pop the first tile using a suction cup, or break it out so you can cut through the tabs and not damage the wall. 2. Use the putty knife to wiggle through 2 "revealed" tabs of an adjoining tile. Remember the tile edges are sharp and can cut you. 3. Get a special tool. Spring steel the thickness of a putty knife. I would go to a local metal fab shop and have one made up on the spot. 10-20 bucks should do it. 17-18" long with the last 3-4" bent 90 degrees. 2" wide. Wiggle that in to cut through the distant tabs. Shouldn't be a problem as the tool will flex and the tiles do flex a bit. Again, watch those sharp edges.
What you'll have is an undamaged wall with pieces of tabs all over it. They are easily scraped off with a flat razor knife. Were for me anyway.
Did I mention she made me take off the plank paneling on the lower 3' of that wall? Yep, it was on with liquid nails. I don't want to talk about that right now,