Remove the lid from the paint can and make sure the leftover latex paint is dry.

Dry latex paint can be then disposed of with bulk garbage, on your last regular garbage pickup day of the month.

How do I dry out latex paint?

If the paint is not yet dry add kitty litter, sawdust, or strips of newspaper to speed the drying process. 

If you have a large amount of leftover paint, consider donating it to a neighbor, local charity, or theatre group.