Select a Space inside the Design World by left-clicking on the Space object, which automatically highlights the Space in red:
Left click on any of the Space boundary lines and drag it to the desired position in the Design World -- in this example, downwards:
This example is a case where some of the objects previously bounded by the rectangle shape that defines the Space objects are not inside the rectangle anymore. Its important to understand that when moving a Space, it does not move everything contained within that space.
Moving boundary of a Space object in the Design World can result in some objects no longer being contained by it. In this example, after re-positioning the Space object, the top Rack object is no longer contained inside it, which can also be verified using the Space Editor's Equipment tab.