Within Revit, you can add a room and then delete it from the model. Revit, however, still holds onto the room information, and considers these as "Not Placed" rooms. These rooms will not "physically" exist until the room is re-placed.
Rooms can also be copied and placed, creating duplicate rooms. Duplicate, or redundant, rooms are handled, in Revit, by assigning area and perimeter to one of the rooms, and leaving the value as 0.00 for its duplicate.
Assemble, however, pulls geometry for both of these room conditions, based on their last known locations, as this information is still stored in Revit.
To void your Assemble model of both data and geometry for these room conditions, you can use one of two methods.
1. In Assemble, apply a filter where Area != 0.00 (area is not equal to 0).
2. In Revit...
A. In your Revit room schedule, select all rooms that show an area value of "Not Placed", and then delete the rooms from the schedule. This deletes the room name, number, and geometry completely from the model. Remember, this only works in schedules. Deleting a room from a model view does not actually delete the room; the room becomes "Not Placed."
B. "Redundant Rooms" can also be deleted from your Revit schedule. Or, to keep the room information, you can divide the redundant rooms into multiple rooms by using room separation lines.
Note: Spaces and Areas behave the same way as rooms within Revit. Apply the same rules to achieve your desired results.