Crop effect in a polygon

[Rizwan Javaid]

I have a polygon, and I want to achieve this  effect. Basically I want to crop a region from a polygon. Is it possible through snap.svg

[Blaine Simpson]

Two L polygons.

If you don't really need transparency but want the erase area to just have same appearance as a static background color (white in your presentation), just write the white square after the larger square.