Can anyone direct me to instructions on how to remove old glass block windows?

A friend of mine wants to remove approx 15 glass blocks that form a window in a bath. He wants to replace the solid glass block with a window that can open. These glass blocks are old. I can find directions on how to install glass block, but nothing about how to remove it. Maybe it's a job for a professional, maybe not, but I thought it would be worth looking into.

 

If they are old, they are probably mortared in place. You can carefully chisel out the mortar holding them in, but you risk one bad shot, and cracking the block. Use a 1/4" or 3/8" cold chisel and a light hammer, tapping lightly. It will chip out, and eventually you will weaken the hold it has on the block. Of course if saving the block is not in your game plan, eye protection, a crow bar and hammer will make light work of it. Tape up the block with duct tape to keep pieces from flying off, and break out the middle ones first.

 

Have done this before...and managed to salvage the blocks. Try a grout removal tool. No joke. For the extra hard spots, I used a 4" masonry grinding wheel on an angle grinder.
I started around the perimeter of the block window and removed all of the grout/mortar. Don't forget to remove the trim/casing first. Then, with 2 people on the inside to catch and 1 on the outside to push and wiggle the unit, we removed it in one piece. Once the window was out, it was quite easy to remove the old mortar. Believe it or not we had the old window out and the new one installed in 2 hours. Quite dusty though. I suggest closing the door and sealing yourself in with masking tape around the door - or build a dustwall...

Good luck!