I have a little "obsessive compulsive disorder" that always want to place things in an exactly and symmetrical position.

Unfortunately, I built 2 entrances in the wrong places. One is under my claimed land and one is under the land of my friend.

I really want to re-build it, otherwise I will feel very uncomfortable.
However, I can only remove the entrances at ground 0 and -1.
Could anyone help me to remove the entrances from ground -2 to -3?