Above help was correct if you split the 10gig file then u put all split files in that pak32 folder, that folder will be in the same directory as the 10 gig file, now you have 2 options, because you split the files you can delete the 10 gig file and play off the external and you are done, or you can delete that pak32 folder and all those files, and ftp the game the way it was when you downloaded it.
i believe you already ftped the whole game so its best to delete the eleven files you split, thats not how you split psarc files, you use psarc gui to do that, which would not be #666 files when u split the 10gig file correctly you will get 2165 files i think, somewhere around that number. and those 2,+++ files would go in your pak32 folder, so simply put:
Delete pak32folder and 11 files
play game from internal
Use psarc gui to split files to pak32 folder
delete 10 gig file
copy pak32 folder containing 15.6 gigs of extracted files to same directory that 10 gig file was in
Play from external