2006 Chevrolet Cobalt fuel tank

Don't know what you mean by "octane" but all those chemicals aren't going to help. By trying to start the engine, the water has circulated through the fuel rail. Draining the fuel from the tank won't get anything out of the fuel rail. The additional problem is the fuel pump won't run unless the engine is rotating, cranking in this case.

You didn't list the engine size so I have to guess you have a fuel pressure test port on the fuel rail and no fuel return port or hose. You can draw fuel from either of those, then bypass the fuel pump relay to make the pump run continuously. That will get the water out that's near the injectors. Next, stick in regular gas, then continue to draw some out of the fuel rail so that new gas will get up to the injectors.

By cranking the engine you've injected water into the cylinders and that might be condensing on the spark plug electrodes and shorting them out so you're not getting any spark. Try a little starting fluid. If the engine doesn't fire on that, remove the spark plugs and see if they're wet.