If you turned the petcock off and let the bike run till it quit then the carbs are already drained.
I think its a wash - if the fuel stabilizer works as intended then its better to leave the carbs full of gas, so the alum parts wont oxidize (same reason you keep your tank full, so it wont rust).
If you somehow got a bottle of bad stabilizer then draining the carbs is better, but you will have a gas tank full of gunk anyway, that will fill your filter with gunk. If that happens draining the tank and replacing the fuel filter should be all you need to do.
You should never have to take the carb apart on any vehicle - ever. The carbs on these bikes are not intended to be taken apart and put together over and over. The first time you try it, and strip out the screw heads, that will become obvious.
Edit: I just looked at your photo: NO! do not turn or take out screws on your carbs unless you are sure you know which one is which. Some are very carefully adjusted, and if you turn them you "screw up" the carbs.
When I was a teenager I worked in a neighborhood TV shop. Sometimes people would take the back off their TV when it was not working right, and see all the capacitor and inductor tuning screws, and grab a screw driver and "tighten them all up" because they looked loose. That was a $100 repair to re-tune all the filter circuits in the entire television.
Last edited by KCW; 11-22-2017 at 08:22 AM.