Select Define Reference Plane tool and click on face of object.
Use Drawing tools to create a 2D shape.
Select Slice tool and in Tool Options check Heal option.
Select object to be sliced first, “wall”, then select slicing shape second, “line”.
Use Delete tool to delete slicing lines and any intersection pieces you don’t need.
Note, the line slices through the object perpendicular to the current reference plane so be sure the reference plane is positioned correctly before the slice operation.
