2 --3Tb Hdds And Whs 2011

I have a dell server with 2--3TB hdd's that I use for my server, now I want to reformat and repartition the drives. when I first loaded WHS 2011 I didn't partition the hdd's so I lose a TB of space on each.

Now I want to start over and repartition the drives to useful partitions.   what is going to be the best way to do this???  the info on the hdd's is all backed up  else ware.