Stained Glass Cheat to Transform into Clear Glass [duplicate]

Solution 1:

There is no command to change all stained glass in the entire world, but you can use /fill with replace to replace blocks of a certain type in an area with a different blocks.

This command would replace all white stained glass in the selected area with regular glass:

/fill <coordinates for 2 opposite corners of the area> minecraft:glass replace minecraft:white_stained_glass

Your situation is a bit more difficult, because you want to change more than one type of blocks at once. You could repeat the command from above for all types of stained glass, but you would need 16 commands for that.

Minecraft has an impermeable-tag that happens to include all solid forms of glass (no glass panes). You can use that instead to change all types of glass at once:

/fill <coordinates for 2 opposite corners of the area> minecraft:glass replace #minecraft:impermeable