You can only transfer ownership of a tado° device if you own it and it is not rented.
If you own your tado° devices, here’s what you need to do to ensure that the new owners can use your devices:
1. Invite them to join your tado° Home.
2. Once they have accepted your invitation, they can update their contact details by going to Settings > Home > Home details.
3. Next, you either need to remove yourself, or ask them to remove you from the tado° Home by following these steps.