How to erase disks in a RAID controller?

If hard disks are part of a RAID (software or hardware), they are not visible in the system on their own but presented as part of a virtual disk which can be erased as a whole. If there is a need to erase individual disks, they must be taken out from RAID configuration.

For software RAID (like Microsoft Storage volumes) a RAID should be broken, all individual disks from the RAID will become individually visible and accessible for erase.

For hardware RAID (configured on RAID controller) disks must be physically taken out from the RAID controller and connected to the system directly in order to become accessible as individual disks. Some newer controllers can allow you to disable them and break apart the RAID. Please consult your RAID card's manufactures manual.