Disassemble a RAID 1 arragement without removing/reinstalling the system

I've set up a Soft Raid 1 using Debians built in RAID systems. I set up the raid because I had a space HDD when I set up the server and thought why not.

Now, how-ever I could really use the disk for a much more useful purpose.

Is it easy to discontinue the raid without having to reinstall the OS, and how would I go about doing this?