How does one clip a '3D volume' in a building?

How does one clip a '3D volume' in a building? For example, one has a 20 story building, 20 rooms on each floor, based on coordinates and elevations, how does one clip a volume out of that building in 3D, e.g. floor 18, room 12? One would think one should be able to specify a volume or coordinates and eliminate much of the drawing to detail just the volume interest.

Note, I am a new MS user (company constraints) who "used" to be an AC expert (long while back and 'self-proclaimed').
I am not a drafter, but use a MS 3-D model for reference and "modeling / drawing" intermittently. I have a 3-D plantspace model of a huge facility that I am trying to navigate, partition, and input 'minor' modifications / manipulations.

MicroStation V8 XM Edition, v8.9.4.88, Design Series Modeling