[Resuelto] how to change the URL or to perhaps change it back to development mode

Hi there, we have just switch one our websites to production in order to transfer the site to the client. However, the website still hasn't gone live so I entered the 'development' url as the production site url. But this will need to change once the site has actually gone live. I now can't see how to change the URL or to perhaps change it back to development mode and then transfer it to the client once it's officially gone live.