I think you should be able to add a file called:
/etc/modprobe.d/blacklistbluetooth.conf
containing:
blacklist bluetooth
which should prevent that module and its dependencies
being inserted into the kernel.
If you want to avoid rebooting, you might be able to:
# rmmod bluetooth
but you might need to remove modules like:
btrtl,btintel,bnep,btbcm,rfcomm,btusb ¹
first, and they might be busy.
¹ lsmod or /proc/modules tells you which they are.
Cheers,
David.