I have a Macbook Pro running Yosemite, but no iPad or iPhone.
Photos.app transferred the entire contents of my iPhoto libraries, but I cannot see how to delete an unwanted event. Although I am using Photos.app, and iPhoto has now gone, the events are still referred to as iPhoto Events.
It is my belief that the lack of "iPhoto" as an app anywhere on my system means that I am running wholly on "Photos" despite the events being referred to as iPhoto Events.
Am I correct in this belief?