my friend's bike was sitting for 9 months with gas in the tank.  We drained the old gas out but I have no idea how I can dispose of it.  Where can I go?

Oh Yeah, if you need to store your bike for an extnded period, go to your local municipal airfield...the small fixed wing strip, and buy aviation gas. They can't pump it into your bike or car, but most will pump it into an approved container.

I ran a 1976 Goldwing for years. If I let it sit for two weeks with pump gas it would not start "period". I could put aviation gas in it and leave it for nine months or a year. With a fresh battery charge and the float bowls primed it would fire on the first crank. The same can be said for a 250 Honda Helix.
Drain the pump gas out and run it dry. Then refill with aviation gas and run it around the block once or twice.

As I was recently registered with the State of California as an Environmental Assessor, I am familiar with the laws in CA concerning the disposal of your gasoline.  As you are an individual and not a business, legally you can do one of 2 things.  You can use it for the purpose it was intended by pouring it into any gas tank, or you can call your local city hall and ask them the location of the next community hazardous waste round-up and give it to the trained techs who will identify, correctly package and dispose of your waste gasoline.  In some areas, the city will have hazardous waste collection days where they will pick it up from you at your residence.  The easiest legal thing to do is walk up to one of the million illegal aliens in CA and ask him if he wants some free old gas.  He will immediately take it from you and dump it in his gas tank

I've run my old gas thru the lawn mower(with inline filter) and had no problems. Besides, unlike a motorcycle, if the lawnmower stalls, pushing back home is not a problem.