Take that little thing off and soak it in a coffee can with about 4" of lacquer thinner. It's cheaper than carb cleaner and is just the same. But, you really need to disassemble the whole thing and go at each and every little hole, both in the body of the carb and the jets that unscrew.
You can get a cheap siphon line (bulb pump) and get most of the gas out that way. Then take off the metal crosspiece under the seat, lift up the plastic battery carrier/panel and coax the gas tank up and out as far as you can. You should be able to reach the two fuel lines at the bottom front of the tank. Release the pinch style hose clamps, Make a note of which hose goes where (color coded stripe) Then pull off the hoses and quickly plug the nipples with you fingers until you get the tank free of the frame. Let the rest of the gas drain into whatever you have to collect the gas. Then clean it out good. You can use air there, too. That's how I would do it. Now, it's somebody else's turn.