Dell Sudio XPS 8000 running W7 - How to remove secondary plex from mirrored HD

Hi,

I got a new HD to run set up and run as a raid 1, mirrored drive, on Windows 7, to back up the original HD and intended to keep in place as a mirrored disc.

Once it was fitted I used the Computer Management, Disk Management, created a mirrored drive using the add mirror. I did this over the system reserve and C Drive (data). All loaded fine and gave me the secondary plex on boot.

The disc was clunking and making a noise, so had it replaced with a new one.

When the replacement arrived I removed the faulty one and put the new one in and repeated the above. At this point I was not aware I had to remove mirror through disk management and as a result I have two secondary plex options on boot.

Can anyone advise how I go about to remove the secondary plex option that was attached to the faulty disc, and is now redundant.

Thank you Leigh