As only one device can be linked per room, attempting to pair a room that already has a device associated with it will result in an error (warning) stating, "This room already has a device associated with it."
If you no longer need a device that has already been linked:
Go to Management Console > Device Management > Click "..." on the right side of the device you wish to remove > Delete
This will unpair the device from the room, allowing you to re-link the necessary device.
Device Management Screen:
