If you want to remove a Roost Smart Home device from your account follow these steps:
Open the Roost Smart Home app to your home screen. If you have more than one address in your Roost app you may need to swipe left or right to get to the correct address.
Tap on the a device tile in the room view (for example, Basement) to get to the expanded tile for the device.
Tap one more time on the expanded device tile to get to the device menu. Then tap "Delete"