Got it. Thanks
You're right, it was a bit hard to follow. I selected each item individually, roads first, and converted back to a polyline. Once I converted the roads I was able to do the same to the terrain line and then delete it. I had been staring at the screen too long and missed the obvious.
What was throwing me off was that if I converted the terrain line to a polyline first then the roads disappeared but converting the roads first had no effect on the terrain line. Either way, I eventually got there.