To edit/upload/save/delete files via FTP, you will need to connect to your server via an FTP program. To do so, please follow the below instructions:
Stop your server from the panel.
Log in to FTP using WinSCP (a free FTP software) using the connection details found in the "FTP Details" section of the game server control panel.
Download link for WinSCP here http://winscp.net/eng/download.php
Navigate to the directory or file that you want to edit/delete/upload/change.
If you need help locating specific files for your game server, please feel free to ask!
After you have finished, save your changes and restart your server from the control panel. You do not need to close out the FTP connection to do so, but you will need to close out any open files.
If you have any questions, or have issues accessing your FTP service, please let us know.