The simplest way would be to take them back where you got them, for disposal in their normal waste stream (which I presume and hope is via suitable recycling or destruction, rather than into drains or landfills).

Failing that, I've heard of folks leaving the chems in pans or similar to evaporate, then disposing of the resulting powder at community haz-waste pickup days (when the local waste authority will take in things like old cans of paint, car batteries, etc., usually without the surcharges that would apply for disposal of those items with regular household trash). You could probably do the same with the liquids, if your haz-waste takes liquids (some don't).