Hello -- I have just updated to El Cap GM and a folder called "Previous System" now appears on Finder. I googled about how to get rid of it, but when moved to the Trash and trying to empty it, a message pops up saying that "some items are in use". Do you folks happen to know a workaround for this? Deleting this folder would make me save gigabytes on my MBA SSD. Thanks a lot! Mark.