Latex (Acrylic) Paint:

Latex paint is
NOT considered hazardous material. However, liquids cannot go into landfills.  If the can of paint is less than half-full you can add an adsorbent material (like kitty-litter), mix it up and allow it to dry. Once dry, it can go into your regular trash. Also try giving paint away to charities that may be able to use it. 

Oil-based Paint, Paint Thinners, and Lacquers:

This is material is considered household hazardous waste and must be disposed at a Household Hazardous Waste (HHW) facility.