Answer by Jeremy31 for I have two usb bluetooth adapters one doesn't work (hci1) but seems to be the default. How do I disable it so I can use the other one (hci0)?

Your internal one can be made to work with firmware

wget https://www.dropbox.com/s/9oujf7jzgy73z4m/BCM43142A0-0a5c-21d7.hcdsudo cp BCM43142A0-0a5c-21d7.hcd /lib/firmware/brcm/sudo modprobe -r btusbsudo modprobe btusb

But since the question is how to disable the internal

sudo gedit /etc/udev/rules.d/81-bluetooth-hci.rules

Then enter the following

SUBSYSTEM=="usb", ATTRS{idVendor}=="0a5c", ATTRS{idProduct}=="21d7", ATTR{authorized}="0"

Save, exit gedit, and reboot, the internal card will not show in rfkill list all