You server probably already has bluetooth disabled or off. Just in case, you can double-check and if the service is enable, here's how you can disable it.
To disable bluetooth service on startup, you can add the command to disable it in the /etc/rc.local file.
sudo vi /etc/rc.local
add this line before exit 0:
rfkill block bluetooth
You can also disable it on boot in the main configuration file.
