Index Page

I am revamping a very old site with a lot of pages so it is going to run alongside the existing site until I am finished.
I have loaded WP to the root folder of my directory and to reach it the url is https://www.mysite.com/blog, my question is when I have finished the work how do I get my “WP” index to be my home page for my site ie https://www.mysite.com