How to remove the large expansion door in space stations.

I've been changing the walls in my space station, and I've removed the tile protection. So far it's been going well. That is until I came across a problem. The expansion doors are preventing me from changing the walls they rest on. They are still protected. Is there any way to remove them? And I don't mean hide them, seeing as that didn't work either.

Also, at this point in time I can't use mods to fix it.

 

the expansion doors dissapear if you wall them (background walls) around enough