According to the Aran Environmental website, you can store nitro methane, the main component of model aeroplane glow fuel, for an extended period of time if the container is tightly sealed and kept in a cool, dark, dry place. If not stored properly, the other component in glow fuel, methanol, attracts moisture which eventually renders the fuel unusable. You can reuse model aeroplane glow fuel but you'll eventually need to dispose of it.
Reuse old model aeroplane fuel as a cleansing agent for the engine you've nosed into the ground. It's especially good at removing old mud. Use old rags, toothpicks and an old toothbrush to clean hard-to-get-at engine parts.
Label your container as "Hazardous Waste."
Find your nearest hazardous waste disposal site and dispose of it. Go to the Earth 911 website (see References) and click on your state, then click on "Programs and Resources." You'll find contact info for your state's Department of Environmental Services and other hazardous waste related contact info.
Do not dispose of old model aeroplane fuel in the trash, down the drain, in the sewer, or in a remote spot in the country.