RAID is an array consisting of more than 1 drive. You will have to break the array (doing this will most likely destroy all data on all the drives in the array depending on the array type, but for all practical puposes, just plan on this happening.) You can simply go into your BIOS, and disable the RAID controller. Set the drives to standard SATA devices, and then they will show up as individual drives to format or do with as you please. Be warned, if your OS is operating off this RAID array, IT WILL BE GONE TOO AND YOU WILL HAVE TO START OVER FROM SCRATCH BY REINSTALLING YOUR OS.
It is obvious that you have little experience working with RAID arrays, I would whole heartedly suggest finding someone knowledgable to help you do this...