is there a way to delete devices from my playbook that I no longer need to bridge with?
Of course! On the Bluetooth settings page, tap the edit button (the little pencil icon) then tap the trash bin that appears next to the device that you want to delete.
Assuming you changed phones, then. I had the same thing.
Noticed that I couldn't delete the other device. But it seems to have disappeared after I restarted the PB sometime later.
Other than seeing it on the list, does it cause some sort of problem? It did not for me.
David