A remote DS device cannot be unassigned without the use of a manager device. See section 2.13 Unassign a Remote DS for more information.
You can utilize the enroll button from the SmartCircle Remote DS app to assign the remote DS device to a different fixture and position.
Attention: If the device is enrolled in a different location it is not unassigned from its initial position. If a new device is enrolled into the same position as the old one, it overwrites it.