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
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.
sudo vi /etc/bluetooth/main.conf
And set InitiallyPowered to false:
InitiallyPowered = false