Try to in to the Console screen and go to Extended tools ctrl. + alt. + x then select "Delete Unit" . You can also select Restore default Configuration (ALL) after you delete units - use only when you are needing this system to be in it's original state.
However, I'm not able get infront of the device I'm connecting to this via a web browser (suppose should have mentioned that before). Is there any way of doing it from the web interface?
Restart the system - then hold the Escape key after POST boot. You will be in a menu screen select - NAS Rescue Mode - then you will be able to get in the Console.