If you have root-level access to a hosting server, it indicates that you'll have full control of it. In other words, you'll be able set up any server-side app regardless of the changes that it will make to the software environment on your server, and you will be able to both access and update any 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 the aforementioned things as well as to make other users, which includes users that 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 make one more user for your everyday work and employ the root user only when you need to customize the server or to install software that may be required by some script-driven application that you would like to run.