How do you get the identifier from the ring app (or ring web site)?

How do you get the device identifiers, the numbers next to the QR codes, from the ring app or the ring web site? This is for devices that are already set up, visible, and working in the app. Some explanation on why: I am selling my house and leaving the ring hardware for the new owner. I know I have to remove all the devices from my account and the new owners will have to set up the devices in their own account. However, because the hardware is already installed, and the original packaging is long gone, I would like to leave the new owners a list of identifiers for the hardware so that they don't have to go poking around and removing pieces looking for the QR codes. I don't want to do that either. Rather, before I delete the devices from my account, how do I capture what the identifiers are?