Replacing an account using the url path

Hi, I have two wordpress accounts setup on my server. The first is sitename.com and the second is sitename.com/wp/. I want to replace the current site (sitename.com), with the second site (sitename.com/wp/), but then display the second site without the /wp/ and have it as the same url as the first but with the new sites files and plugins etc.

I’m completely stuck on this, can anyone help? If I didn’t explain this right please just ask for more.