Hiding URL code

I have a web hosting. I wanted to set up a new website. I bought the domain name and I have it redirecting to where the new website is.

Currently if you go to mynewsite.com it looks fine, but if you click on the home button, pages or posts, the url in the box views https://www.oldsite.com/mynewsite/whatevethepage name.

I want the site looking like its a completely new and independent site. So what ever links of it looks like mynewsite.com/page1