"Unable to Deregister Device" Error

You will only see the "Unable to Deregister Device" error message if you are trying to deregister a device that currently has a Dp DOCK registered/paired to it. 

You must ensure you have your Dp DOCK powered on and press 'Deregister Dp DOCK' on the Pen Details page to deregister your Dp DOCK.

Once the Dp DOCK has been deregistered from your device, you can go ahead and Deregister your device.