You can purge old users by date from the admin menu (Delete Inactive Users) - that does not take into account their post count.
Deleting members that only have a 0 post count isn't currently a feature. I did write a modification to do this
HERE at ThreadsDev. Haven't had the need to update for 6.4. yet - but the instructions may still work for you. <img src="https://www.ubbcentral.com/boards/images/graemlins/smile.gif" alt="" />
