If you want to get real picky, draining them is the correct method, running it until it stops only lowers the fuel level in the float bowl, it doesn't drain it, so some fuel is left in the carbs. Every time this question is asked you'll get a dozen different methods and each person says they've been doing it this way for years and have ?no problems?. What this means is that not many people have problems no matter how they do it, so find a method you want to believe in and sleep well.
My method is to turn off the key, at that point it's ready to sit for whatever amount of time passes. Been doing it that way for years, and I have "no problems".
