There are a number of ways to make irrregular openings or other cuts in walls:
1: Lateral: Empty Window opening - place in wall
2: Any Direction: Solid Element Operation - use a slab or other shape to make your cutout.
3: If an irregular shape - make the shape as a slab, save the slab from the side as a library object (ie: flop on its side) use the irregular shape in the wall with the object as Solid Element Operation.
4: If related to roof components: Use "Trim To Roof" to cut wall - delete or hide roof afterward.