To turn off Punkbuster your server must first be unranked.
Edit the code into your Startup.txt config.
This can be found here: Clanforge -> Your Server -> Edit Profile -> Config -> startup.txt from the drop down menu
Hit Save & Apply to apply the changes.
#Will the server be ranked true/false vars.ranked "false" #To password the server, must be unranked vars.gamePassword "$$game_password$$" #$$variables pull the password from the settings tab