After moving WordPress to a new directory should previous core files be deleted?

I’d installed wordpress in a sub directory of an existing site in order to work on the new site design. Afterward, according to the Codex instructions, I changed the settings in the admin panel and copied the core files and index PHP to the main directory. Everything is working.

But my question is, do I delete the core files that are in the sub directory or will this melt down the site? I don’t know if something in WP is still drawing information from those files or not.

I’m worried that if I leave these duplicate files in the the working directory that Google will see it as duplicate content.

Thanks in advance for your help.