Please post back a screenshot of your maximized Disk Management drive map and listings:
1. Type Disk Management in Start Search box.
2. Open Disk Mgmt. window and maximize it.
3. Type Snipping Tool in Start Search box.
4. Open Snipping Tool, choose Rectangular Snip, draw a box around full map and all listings.
5, Save Snip, attach using paper clip in Reply Box.
Tell us what is on each partition.
Check also the BIOS settings to see if you have a RAID controller pop-up when you first boot the computer which must be disabled in additon to the setting change to AHCI.
You'll likely have to move your data off the RAID first to unRAID it.