When you have root-level access to a server, it indicates that you will have full control over it. That is to say, you'll be able set up any server-side app regardless of the changes that it'll make to the software setting on the server, and you will be able to both access and change any kind of file, which includes system files, and modify various settings. You can do this by connecting to the server as a root user who has full privileges to do all these things and also to generate other users, which includes users that also have full privileges. This particular can be established with a web-based graphical interface or a Secure Shell console. For security reasons, it's recommended that you make another user for your everyday work and employ the root user only when you have to customize the server or to install software that may be required by a script-driven app that you'd like to run.