Back up your important data first. I won't be held responsible for any loss of data.
This guide writing for DMS 6.1.3, use a single HDD.
>>> Proceed at your own risk! <<<<
Power off your XPE.
Insert a new HDD (equal or greater capacity).
Power on your XPE.
Change RAID type: Open "Storage Manager" >>> RAID Group >>> Manage >>> Change RAID type >>> RAID 1 >>> Drag & Drop the new