Yes you can but you might want to hold off on that if you have iPhoto 9.6.1. If you have any intention of creating a photo book with Photos be aware that Apple no longer offers these books and they must be obtained thru 3rd party software and book providers. Using the 3rd party software is not the easiest to do.
However, if you have iPhoto 9.6.1 you can create the books, save them was PDF files and order them thru one of two online providers that will accept the pdf files to print and bind books.
If you don't have any plans for photo books then go ahead and delete the iPhoto Library (make sure you have all of your photos in the new library beforehand). I'd keep the iPhoto App as it doesn't take up that much room and if you decide you might need it later on you'll have it. Delete it and you may not be able to get it back.