If you've already moved them, there's probably no need to do it again. Umfriend was describing in "Wrt step 4" how to move the location address of the files within each individual drive (E: then F: then G:) rather than physically copying and deleting the files themselves.
As you probably know, if you move a file, no matter how big it is, from one folder to another using Windows/File Explorer, the action is almost instantaneous since Windows simply points to the new location -- like changing the page number in the table of contents or index. You can do the same thing by moving files between the PoolPart.* folder (that represents the DrivePool pool) and another folder outside of the PoolPart.* folder on the same drive (e.g., E:).
So if folder PoolPart.xxxxx represents Pool A on Drive E: and folder PoolPart.yyyyy represents Pool B also on Drive E:, you can move the files between those two folders quickly, since the operation would just change the address of the files. The long alternative would be physically moving the files into the drive letter that represents Pool B.
Again, if you can confirm that the files are now in Pool B, you completed the race but didn't take the shortcut.
I guess "upper" and "lower" PoolPart folders is how they are sorted in Windows Explorer, and PoolPart for Pool A is named closer to "A" in the alpha sort, maybe because it was created first?