People who no longer reside in New Haven are still on the list of registered voters

During the recent election I discovered that people who used to live in a rental property I own, several of whom have not lived here for years, are still listed as registered voters in New Haven. With a little bit of imagination, it becomes clear that in this city, with such a transient population, it's likely that the statistics re: registered voters/# of such who vote in any given election, etc., will be really inaccurate, which is not a good situation. There must be a way for City Hall to clean up these records. It is important and necessary work, though I'm sure massively tedious; how do we get this done?