Pretty much what hardwood said, but it might be wise to save the old queens for a couple days to make sure the new queens are accepted.
The best question is, "why do you feel the need to?".
I seen a guy on youtube kill a great laying queen, a solid brood pattern, because he bought a queen from a place in NY that was that was advertised as "mite resistant".
Later videos showed him still treating for mites, along with other stuff that he didn't have.