The Split tool is extremely useful cutting and splitting objects. For example you could use…
Vectorworks Tip #060 – Basic Tools – Split Tool
If you need to cut or split objects, you will find the Split Tool ideal. It can split objects or it can trim them. There are three modes. The first mode is used to split an object and it works best with linear objects like walls, lines, etc. The second and third modes work best on objects that have an area, like polygons, floors, landscape areas, etc.