If you are trying to recycle an old generator, consider selling it to Green Recycling Co. This company specializes in refurbishing a wide array of commercial generators.
There are several other companies involved in the refurbishing of used generators for a variety of purposes. You can break generators down for parts or upgrade them to modern standards; however, recycling your generator at home would be a laborious process, so it's usually better to find a local professional to handle it for you. Many companies cover the transportation and other costs of recycling the generator, so it's generally hassle-free for you.