Hi Querl28. There's a few different ways.
Simplest is you install the replacement drive, tell DrivePool to add it to the pool and then tell DrivePool to remove the old one from the pool. DP tell you whether it successfully moved all the files on the old drive across (in which case you can then physically remove the old drive) or not (in which case you have to decide what to do about it).
If you don't have spare ports to add the new drive before removing the old one, but you have enough free space on your other drives in the pool, then you can tell DP to remove the old drive from the pool before you install the new one.
See also this support page on removing drives.
