Something odd going on there.
So you are saying you can't just delete an 'original' layer because the elements remain in a 'missing' layer.
But you can delete the layer and move all elements to another 'temp' layer.
Then you can delete that 'temp' layer in just the same way that you tried to delete the 'original' layer and all of the elements delete as well.
If that is the case, I can't see what the difference would be.
I would be contacting your local support people and asking for help.
PS - does Find & Select searching for all elements with attributes missing help find them?
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10