Units are meters. Hover a roof plane to preview a fixed 0.60 x 0.90 m skylight. Click to place it, click a skylight to select it, then delete it.
The roof is a generated slab with interior and exterior faces. Each opening is rebuilt without CSG: the top reveal is horizontal, the bottom reveal is vertical, and the side reveals connect those two cuts. Use Delete or Backspace to remove the selected window.