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