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In article .com, wrote:
The "use a different nozzle from another can" is the easiest and
cleanest method, as long as the paint tube isn't clogged. However, if
you really need to depressurize the can, I would think you'd want to
punch the hole as far from the pool of paint as possible. Stand the
can upright on your bench, and leave it for awhile (15 minutes?), so
that all of the paint settles to the bottom of the can. With the can
standing upright, punch the hole in the metal top (but not where the
nozzle tube comes through). The smaller the hole, the better. The air
escaping from the small hole should not take much paint, if any,
through the hole, because the air isn't pushing paint towards the hole
in the top. When the pressure is gone, you can then use some kind of
tool to open the can and pour the paint into a small bucket or similar.

Or, maybe I don't fully understand how spray paint cans work?

I've done this with small nail. Works fine. Once the pressure is gone,
put another hole in the rim on the opposite side for a vent & pour the
paint out. It's pretty thin for brushing, but the solvent evaporates
pretty quickly, so it will thicken up a bit if you let it "breath". It's
been a while since I did this. I think I put the can on the floor in the
middle of a sheet of newspaper, and held the nail pinched in another
sheet to absorb what little spray there was. I tried to make a very
small hole, and then held the nail in place while it vented slowly.

Doug White