How to delete photos in iPhoto

Deleting Photos from a Photos 1.3 Library

1 - regardless of where you are in the library, i.e. Moments, Collections, albums, smart albums or projects, select the photo(s) you want to delete and use the key combination of Command+Delete to move the photos to the Recently Deleted smart album.

2 - click on the Recently Deleted smart albums in the sidebar.

3 - in the Recently Deleted album you can opt to let the photo automatically delete after the 30 day waiting period is up, delete them immediately or restore them to the library.

NOTE: deleting a photo from an album, slideshow, book, etc., with only the Delete key only deletes that photo from that item. Deleting a photo from a Moment or Collection deletes ALL occurences of that photo in the library.

What version of iPhoto?

In general: Select an image in the Library and tap the delete key or drag it to the iPhoto Trash.

Then empty the iPhoto trash, and with iPhoto 11, thereafter empty the system trash too.

You need to delete the images on your other devices on those devices.

That's not iPhoto, but the new Photos.app. I'll request your post is moved to the correct forum