I have my static website in hugo, this is the folder structure:
I do not why, when I do hugo -D to build hugo, it generates the following scaffolding:
I just want pricing, terms and privicy page in the root folder after building hugo, with their respective names, not a folder with the name and inside an index.html file.
NOTE: pricing, terms and privacy page are using single.html
Hugo defaults to using pretty links, that is to say ending with a trailing slash and no extenstion. That is what you are seeing output, hugo creates an index file in its own directory.
This means you don't get URLs like example.com/pricing.html, which is generally what people prefer.
If you would prefer a flatter structure, and don't mind your pages showing the .html extension, you should enable uglyUrls.
The URL management documentation for Hugo details both options.