Depends on how much acetone it is. If it’s a lot, like a gallon or more, then take it to a hazardous waste facility near you or offer it to someone who might need it (if it’s still usable)

If it’s a tiny bottle, like acetone for nail polish remover, you can just pour it and let it evaporate in a well-ventilated space. If it’s around a pint, you can evaporate it too, or you can also soak it up with cat litter, then bag it separately for landfill disposal.

Acetone is pretty safe but can be irritating and toxic in high concentrations, so handle with caution and in a well-ventilated area that’s far from any open fire and wash your hands after handling it.