There is no official "owner" of the frame and thus no way to transfer ownership or make someone the owner of the frame.
The owner of the frame should simply be understood as the person who owns the frame and physically has access to it. To the frame, every connected phone is simply considered a friend.
However, it is possible to give a friend permission to share the frame's friend code. You can check out this quick guide for more help: How to Share Friend Code From App.
If you have any questions, encounter any problems, or discover a bug, please do not hesitate to get in touch with us! You can submit a ticket here, and we'll get back to you as soon as possible.