Deleting Photos in Photos on Mac

when you want to delete a photo while viewing an album, use the key combination ⌘⌫ to delete the photo.

Or, if you want to use the "Image" menu, to delete the photo, hold down the command key while opening the menu. With the command key ⌘ held down, the command "Image > Remove from album" will change to "Image > Delete ... photo", the ame goes for the contextual menu, when ctrl-click or right click selected photos.

See: How to delete photos while viewing an Album… - Apple Community

Deleting Photos from a Photos Library

1 - regardless of where you are in the library, i.e. Photos, Memories, Favorites, People, Recents, Imports, albums or smart albums, 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.

NOTE 1: If you're using Photos 1.2 or earlier use the File  ➙ Show Recently Deleted menu option.

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 2: deleting a photo from an album, slideshow, book, etc., with the Delete key only deletes the photo from that item. There is no key combination that will delete a photo from a project and move it directly to the Recently Deleted smart album.

NOTE 3: deleting a photo from a Moment or Collection (the Photos window) or the All Photos window deletes ALL occurences of that photo in the library.

You're welcome 😊