My first thought was to just rip the seam and remove the sleeves. Simple, no? However, after I started ripping, I found that the seam also attached the binding on the short part of the sleeve. Oops. I stitched the binding back on in quite the mediocre fashion. It looks a bit like how I imagine Mary from the Little House on the Prairie series' sewing looked. You know, after the fever that took her sight. The other sleeve I just cut as closely as possible to the seam and left the raw edge inside.
If no one looks too closely at the back of her left sleeve, I'll call it a success! And if they do look too closely, I'll explain that it was mended by a blind girl, struck by scarlet fever and a stroke. If they judge that, they're assholes.