Building error then deliting part of floor on 2th floor

was building a wall and had a road going to the the wall was going to be and latter extend behind it. Then designing the second floor of the wall, I got a bug that prohibits me from deleting a part of the floor.

Steps to reproduce:

  1. designed one side of the wall by pleasing down a bottom floor
  2. adding walls
  3. added a second floor on top of the wall
  4. added a brim to that floor, that later wold be the coronal of the wall
  5. designed the second part of the wall fooling step 1 to 4, at this point I have two walls on either side of the road.
  6. now I concede the two walls by designing the floor of the second floor together
  7. placed a second voxol the the coronal of the outer side of the wall
  8. was trying to place the back side coronal but I got a error for that
  9. tried to delete parts of the second floor, but just reside errors

Expected Results:
having a wall

Actual Results:
having a ghost wall that is in the way of any new attempt to have a wall

This is the save i encounted the bug
Bugde save (7.4 MB)

Version Number and Mods in use:
stable alpha 16

System Information:
CPU: Intel core i7-4720HQ
GPU: geforce GTX 970M
Ram: 8GB
OS: Win 7 Ultimate, service pack 1