Are the photos gone from All Photos a well, not just from the album?
When you delete a photo from any album, it will be deleted everywhere in the library, from All Photos and any other album it has been added to. The albums are just referencing the photos in the library, they are not storing own copies of the photos. this way each photo is only stored one, independent of the number of albums we have added it to. We have to use the command "Remove from Album" and not "delete", if we just want to remove. photo from an album and not delete it from the library.