If you actually mean "How" to clean it, and not what to clean it with, this is taken from the link above my sig pic.....
Just disconnect your air inlet tube ahead of the sensor, and spray some MAF cleaner through the screen at the little elements in the center of the sensor. Let it sit for 5 minutes or so...,give it another shot, let it sit for another 5 minutes, then start your engine. Some people just use electronics cleaner, but I recommend actual MAF cleaner from the auto parts store. You can also take the sensor right out and clean it that way too, but it's easiest to just spray it where it is. You can hold a rag or something behind it. Here's a pic of what you are looking for. Mine looks a little different on my engine, but it's pretty much the same idea.
