deleting photos

There seems to be a confusion of terminology in terms of which version of Lightroom you are using. IF you are using Lightroom Classic you must add an image to a collection in order for it to be in an album in Lightroom (for the web). However, adding the image to the collection does not create another copy of the image. There is still only one copy of the image. The collection is simply another method of organizing that single copy. In order to have the image in the collection and part of anything in Lightroom, the master image must be retained in the catalog. If the image is deleted from the catalog it will be removed from collections and all adjustments that have been made to that image will be deleted as well.

Is this a Lightroom Classic question? Or a question about the web-centric application named "Lightroom"???

There are no albums in Lightroom Classic.

If you delete a photo from the catalog in Lightroom Classic, the photo is no longer known to Lightroom Classic, and so it is no longer registered in the catalog, and it is gone from anywhere in Lightroom Classic (although it may still exist on your hard disk).