Help, I can't select these objects on my scene

I was modelling a dungeon and then I noticed these objects on my scene. I was gonna delete them but I can’t select them. How do I delete these?

Have you tried selecting them in the object outliner?

blend file. i think i know what it is, but im not sure.

if you open a new viewport and change it to outliner, you will see every object in the scene. next to the object, there should be an

eye (visabilty)
Camera (render)
and cursor (selectable)

click the cursor.

Thanks for the idea. I remember using that a long time ago I forgot it!