Thought it's probably too late for the OP, any significant quantity of
left over paint can be donated to Habitat for Humanity, etc. Otherwise
save it in sealed plastic containers for touch up use later, (save some
anyway!), or let it dry and throw out the dried materials. You can even
spread it on scraps of plywood and drywall, etc, and let it dry and
just reuse the material or throw the scraps away. Most water based
paint now is not terribly bad to rinse out in the yard but you never
know. Unless the can indicates it is somehow that safe, IMO it's
better not to rinse it into the yard. I would definitely not rinse it
into an area you might use for food-producing garden plants, in any
case.