Yep. I did erase the drawing. It took a lot longer than I thought, and I couldn't simply rub away with a plastic eraser. I think it would have been easier if I had just ripped up the paper instead of painstakingly destroying each layer.
The drawing I brought in was one I had completed last semester in my Life Drawing class. I was intensely proud of it, being the first drawing I'd ever done that came out on paper exactly how I pictured it in my head.