For those looking to disable the bluetooth and the built in audio here is a small guide
Disabling rpi3 bluetooth
Here is a link that walks you through disabling rpi3 bluetooth.
Note: you will either need to use the mouse and keyboard or connect to it remotely with SSH:
Disabling in built in audio using raspi-config
Built in audio can be disabled using ‘raspi-config’.
You will need to install it as root or using sudo: (it might already be installed)
# sudo apt-get install raspi-config
Walk through the menus and it should have an option for this.
Disabling built in audio card using command line
Here is a link
It’s pretty straight forward.