In Calc, how do I remove shadow from comment box?

I’m using LO Portable on W7. My comment boxes have a black shadow on the bottom and right sides. How do I remove this?

Choose Format - Graphic - Area - Shadow tab or Right-Click and choose Area

Thanks for your reply; I asked this question because a shadow appeared even with the “Use shadow” box unchecked. But reading your reply gave me an idea.
I checked the box and set “Distance” to 0.0. This had the effect of removing the shadow, though it is a klugy solution, at best.