Sometimes, you generate controller or model that you don't need. You want to reverse the things you've generated. Instead of deleting files manually one by one. Rails has a command for that.
here's the codes.
I was just talking about this the other day to a co-worker who is starting with Rails. He used to delete file by file when mistyping a field or type in the scaffold. I will share this with him so he can remember! :) Thanks for sharing.
There is another useful option called --pretend that previews what it would actually generate but doesn't create anything.