Jr. Sys Admin mistake, Can/Do I need to Un-RAID 0 my drives?

Backstory: Just started as a Jr. Sys Admin, Cleaning up data center, re-purposing workstations I find to update currently used workstations.

I started off with a terminal that had some potential, i7-4790, 8 GB Ram, but only had 1 120GB SSD with Windows 7 pro. I found a 4TB NAS HDD and figured I could just throw that in the system and I'd have a nice little workstation. On boot-up, the system didn't show the HDD anywhere. Except when I opened Intel Rapid Storage Technology app. I saw both drives and it said I could link them in an Array. In hind-sight I should have researched the outcome of this a bit. But, I jumped right in and followed the extremely easy to use wizard. Unfortunately when I rebooted the system and look at my C: drive I still only see 1 drive with 50Gb free of 107GB, but in my device manager I see an Intel Raid 0 with a capacity of 244GB and 122GB of unallocated space. Did I just squander the remaining 3.7 TB? Can I un-raid these, or is there a way to partitian the remaining space into a regular drive?