In the web client (same in the TV client) it would be really useful if there would be a function in the context menu “Delete file” in a single photo/video screen - right now there are just Add to album…, Download File and Get info.
From mobile often you upload a bunch of photos you don’t need, but without this functionality you need to close the photo, then you can delete it and resume the viewing of the photos. This function would really improve the usability of the photo library.