Simply cut off the bottleneck
If I have a very nice bottle, I like to cut off the bottleneck so I can use it as a vase or something similar.
This is quite simple:
Dip a wool thread in turpentine, drain so it does not drip.
Put the thread around the bottle where I would cut the bottle.
Light the wool thread and, once it has burnt down, dip the bottle in cold water.
You'll see that right where the thread was, the glass breaks apart.
Now sand the edges a bit with sandpaper and a new vase or a new glass is ready for decoration.
