Latex products can be cleaned up with soap and water; cleanup of alkyd products requires paint thinner or mineral spirits. The great majority of today's household paints, 75 to 80%, are water-based latex formulations. Most of these latex paints can be disposed of by pouring the residual paint on an absorbent material, such as cat box filler (kitty litter) or shredded paper; let the mixture dry completely, and dispose of it in your regular trash.
Generally, once you have used up the latex paint, a thin film of paint can be left in the paint can to dry. Do this in an area out of reach of children and pets with the lid off. The cans, with completely dried latex paint film, may then be disposed of with your household trash or recycled in a steel can recycling program.