Delete AirBnB email?

Hi all I'm new here and was wondering- when they sign the rental agreement / legal doc I get their actual email which is great- but it still sends to their AirBnB email as well and now. It also shows me 2 emails on the guests profile page. And when I hover on the booking calendar it shows me the AirBnB email. Is there a way that we can get their real email to delete/ overide the AirBnB email once they fill out the rental agreement?

Not sure if there is a better way, but once I have their real email address, I manually go in and (just on the overview page) and "Edit Contact Info" and delete the Airbnb address.