If you have root-level access to a server, it indicates that you'll have full control over it. That is to say, you can install any server-side app no matter what the changes that it'll make to the software setting on your server, and you are able to both access and update any file, which includes system files, and change any settings. You can do this by connecting to the server as a root user who has full privileges to perform all these things as well as to make other users, including users that also have full privileges. This particular can be established using a web-based graphical interface or a Secure Shell console. For security reasons, it is recommended that you make a separate user for your daily work and employ the root user only when you have to customize the server or to set up software that may be required by a script-driven app that you would like to run.