Is it possible to delete multiple rooms on Hevacomp at the same time ? I have built a large building using Hevacomp but I now need to split it into two phases. When i'm trying to delete rooms individually the system keeps crashing.

Is it possible to delete multiple rooms on Hevacomp at the same time ? I have built a large building using Hevacomp but I now need to split it into two phases. When i'm trying to delete rooms individually the system keeps crashing. Is there a better solution ?