Previously used wallpapers

Thanks for the additional details.

Just to confirm, are you trying to delete the wallpapers by going to Settings > Wallpapers or by long pressing on the lock screen? 

The reason we ask is, to delete wallpapers, you will need to do that from the lock screen. To access the options, long press on the lock screen and allow it to unlock using FaceID. Once it is unlocked, you will be able to swipe through wallpapers you’ve used in the past and swipe up to delete on any you no longer want to use.

Kindest regards.

Hi CamLight2,

It looks like you posted your question to us from the article Change the wallpaper on your iPhone - Apple Support. The last sentence in the section tells how to delete selected wallpaper.

Change your wallpaper from the Lock Screen

...

From the Lock Screen wallpaper options, you can also tap the Focus button to link a Focus to a specific wallpaper, customize existing wallpapers, or swipe up on a wallpaper and tap to delete it.

If you have tried swiping up and do not see the option to delete when you swipe up, let us know what happens when you try.

Take care!

Hello CamLight2,

We appreciate the troubleshooting that you have completed. The next step to resolution is to contact Apple Support here: Apple Support

Let us know if you have further questions.

Take care.