You cannot delete the albums, that Photos is creating for you. They will appear automatically, if one of the photos in your library is matching the rules for this album. To prevent the People album from showing, you would have to delete all photos showing people or retouch the people out of the photo.To remove the Selfie album, you would have to delete all photos taken with the front camera. You can hide photos that you do not want to show in any album. https://help.apple.com/iphone/11/#/iphf14943e
Album are not storing albums, so the photos in the albums are no duplicates. Photos is storing a photo only once, but it can be used in many albums. if you delete a photo in Photos, it will be deleted from the photo library everywhere, not just from the album, where you are viewing it.
Photos has two kinds of albums:
- Predefined albums, like Selfies, Panoramic, Live Photos, etc. These albums are smart albums, that are collecting all photos, that match a certain condition. Fir example, the Selfie album is showing all photos that have been taken with a front camera. The Panoramic album is collecting all photos with an extreme aspect ratio. The predefined albums are automatically created, because the iPhone has no support for custom smart albums created by the user. without these albums there would not be any way to search for front camera photos or panoramic photos. You cannot remove photos from smart albums, because they will automatically show all photos in the library matching the rules of the smart album. OS photos can only be removed by deleting them from the library.
- User defined custom albums: If you create a custom album by selecting photos and adding them to an album you created, you can remove the photos again from the album, because the custom albums are not searching for the photos automatically.
On a Mac you can hide the predefined albums from the sidebar. Perhaps Apple will add this feature one day on the iPhone as well, if enough users request it.