Oil-based paint is considered hazardous waste and must be disposed of at a Household Hazardous Waste Collection
If it cannot be used or donated, leftover latex paint should be dried up using the following instructions and placed in your regular trash can. It is NOT a hazardous waste.
1. Make sure the paint can is ½ full or less. If the can is more than ½ full, pour the excess into another container, like a milk jug, coffee can or trash bag.
2. Add a clay-based kitty litter or "speedy dry" paint hardener so that the can is ¾ full.
3. Stir paint/kitty litter or paint hardener mixture.
4. If liquid paint remains, add more kitty litter or paint hardener.
5. Allow paint and kitty litter or paint hardener mixture to dry until it is no longer able to pour.
6. Dispose of can in the garbage.