Undo lamp?

Forgive me if this question has already been answered, but I am having some trouble navigating this forum. I have used ArielVision to turn a skp model into a lamp. I am not happy with the way it's rendering, so I'd like to just start over and try something different, but I can't seem to undo the changes. I have tried selecting "remove all lamp settings", but after doing this I can still render the model. I want to revert back to the original model before I turned it into a lamp. Because I had already saved the model as a lamp, I can't just use "undo" in Sketchup. I would attach the file, but I have tried twice and I keep getting an error message.