Note:

If an element below a significant element (i.e. a primitive) is removed, then the whole significant element will be removed as well. To avoid this behaviour the Remove ONLY command should be used. REMOVE ONLY will not remove the significant element but only remove the given primitive from the 3D view (the primitives that have been added/removed can be seen on the primitives tab of the drawlist form). (Note: if the element being added/removed is significant or above a significant element then ADD/REMOVE ONLY will have the same effect as ADD/REMOVE).