Reset Hard Drive to remove Raid

When I purchased my XPS 8300 it was supplied as a 2Tb Dual Hard Drive Raid 0 stripe. I assumed there would be two 2Tb Hard Drives but in fact there were two 1Tb hard Drives. I contacted Dell and explained that it was more important to have the 2Tb storage rather than the raid. They remotely took over my computer and made adjustments which achieved this. (I do my backups on an NAS)

Three years later I needed more storage so I bought two 2Tb hard drives. I have cloned the complete contents of my drives onto a 2Tb Hard Drive. I then removed both original hard drives and inserted the cloned drive and all works fine.

The problem is that I think somehow when Dell originally fixed my problem they did not remove the raid configuration so somehow I think this is imprinted on my new cloned drive because when I connect the second new 2Tb hard drive in place of the old 2nd hard drive it is not recognised. In the bios (see attached screen shot)  the new 2Tb "C" drive is recognised but the second HD is shown as the old original 1Tb drive when in fact it has the new 2nd 2Tb HD i.e. it is not recognising anything in that drive.

I can see in the BIOS there is an option to reset Disks to non raid but I think this will loose my data and programs.

Any suggestion how I remove all the raid stuff and just get two stand alone Hard Drives that the computer recognises? (without losing all my data!) 

Many Thanks