Point root at subdirectory installation

Hello,

I have installed WordPress in a sub-directory named wp_Portfolio. I am trying to set everything up so that when you go to my main website, it redirects you to the sub-directory without revealing this in the URL.

I have followed ALL of the steps on:
https://codex.wordpress.org/Giving_WordPress_Its_Own_Directory

And after doing so, all I end up with is an error on my main page saying:

Warning: require(/home/user/public_htmlwp_Portfolio/wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in /home/user/public_html/index.php on line 17

Fatal error: require() [function.require]: Failed opening required '/home/user/public_htmlwp_Portfolio/wp-blog-header.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/user/public_html/index.php on line 17

Has anyone ever seen this before and know what I might be doing wrong?
I have changed the permalinks and also the “Site URL” to the main URL and not the sub-directory URL.

Thank you!