If you have root-level access to a hosting server, it indicates that you'll have full control over it. In other words, you can set up any server-side application irrespective 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, including system files, and change various settings. This can be done by connecting to the server as a root user that has full privileges to perform the aforementioned things and also to create other users, which includes users who 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 create another user for your everyday work and use the root user only when you have to modify the server or to install software that may be required by some script-driven app that you'd like to run.