What is a safe and efficient way to replacing an Existing Website with WordPress?

Hello, 

I took over an existing GoDaddy website. I installed WordPress and created a website with a root directory: /webroot/wordpress2. What is a safe and efficient way to make my wordpress2 directory the root directory for the website? Right now the old website is http://oldwebsite.com. I can view my new site's home page with http://oldwebsite/wordpress2.  

Many, many thanks. 

Dean