How to Decorate/remove Decorations on Neighborhood maps?

I'm trying to understand the question... My first thought is that I'd suggest this:
1. Open neighborhood decoration mode.
2. Pick up a decoration you want to remove.
3. Press delete key.

If I see the words neighborhood decoration, I'll imagine these are trees, effects, rocks, etc (water towers, crashed UFO's), everything that's not on any lot.
I really don't get the difference between removing and deleting here...