Right now on my root folder, I have an "Under construction" page. So just an index.html, and a style. Then I have a test folder with Wordpress in it, so my website URL is root/test/wordpress. I want to "upload" the website to the root folder so I see the site instead of the under construction page. I have tried changing the website URL in the Wordpress dashboard but that does not work. I have also tried adding the new address in the wp-config file but that doesn't work either.
If I understand it correctly you want to transfer the site from www.example.com/test/wordpress to the www.example.com.
To do so you have to have access to FTP or CPANEL/PLESK to actually cut files from the old location to the new. When you finished that you can use this tool to make the correct changes to the database( including the serialized part).
Then remove the index.html file and you would be good to go.
This is the tools I used search-and-replace
Sorry actually I'd like to give comment rather create answer but my reputation not enough. You can refer to this document: https://codex.wordpress.org/Changing_The_Site_URL
- The "Site Address (URL)" setting is the address you want people to type in their browser to reach your WordPress blog.
- The "WordPress Address (URL)" setting is the address where your WordPress core files reside.
Dont forget to save your permalink again after create these changed.