Inconsistent info from Intel on data loss when deleting a RAID1 array

[Tom-Bones]

I have a RAID1 volume with two disks that is performing very badly with response times that prevent normal use.  An extended SMART test fails instantly on one of the drives.  Rather than purchasing a new disk and rebuilding the array, I want to delete the array so that I can use the non-failing drive on its own. 

Intel's support article below describes how to "Delete a RAID 1 Mirror Without Data Loss", which is what I want to do.

https://www.intel.co.uk/content/www/uk/en/support/articles/000006188/technologies/intel-rapid-storage-technology-intel-rst.html

In practice, when I access Intel Rapid Storage Technology Option ROM 13.0.0.2075, selecting Delete RAID Volume (or Reset Disks to Non-RAID) produces a warning message that all data on the disk will be deleted.

What is the correct method to break a RAID1 array into separate disks and ensure no data is lost?

The volume is listed as Bootable in the Option ROM, however it is only used for data storage and does not have an OS installed on it.  It is the only volume on the disks. 

[Tom-Bones · Accepted solution]

I'll answer this myself, in case anyone has the same issue.  

RAID 1 (Mirror) volumes can be deleted without losing data if the RAID 1 volume is:

The only volume on the drives
Or
The first volume in a matrix RAID configuration

If you delete the array, both drives will be accessible as non-RAID disks.  If you reset a single disk to Non-RAID, only that disk will be accessible.

It is nerve wracking clicking through the warning in the Option ROM that all data will be lost, but that is not what will happen so long as your RAID1 volume meets either of the conditions above.