How to Delete iPhoto Library, but Why You Probably Don’t Need to
Now that most Mac users have migrated their pictures from iPhoto to Photos app in Mac OS X, when you’re absolutely certain that all the pictures have come through successfully you may decide to delete the old iPhoto Library file on the Mac.
This is usually not necessary due to how Photos importation works with iPhoto Library files, but some users with unique situations decide to do it anyway, typically if they are self managing picture files outside of the original library containers, or if they want to keep things tidy and ditch all remnants of iPhoto.