Deleting photos in my MacBook Air library

Hi

Select all the ones you want to delete, then hit the delete key, or image>delete. They will be put in the "recently deleted" album where they will stay for 30 days before being fully deleted automatically. If you want to delete them fully immediately you can do that from the recently deleted album.

Note that if you are viewing the images in a standard album, you will need to hold the CMD key down while deleting. In an album the default delete command will just remove the image from the album, not from the library.