Yes as above have said, just dry it to a solid and trash it.
This works for both water and oil based paints.
If you have a large amount, line a kiddy pool with some plastic sheeting, and pour in the paint. It will dry faster being in a thinner layer. When dry, wrap up the plastic and dispose.
Or use newspaper. Cheaper, dries quicker and you are not adding plastic sheeting to the trash pile.
