Pi5 disable onboard BT & enable BT dongle?

[twistedd85]

I have a metal case on my Pi5, so the onboard BT only works on a very limited plane. If I angle the controller down it locks up on the last input until it gets back into range. So I bought a BT dongle. I keep searching for how to disable the onboard BT, but all I find are vague posts and "the onboard should work fine", so I'm kind of at a loss. Is there any step by step guide on how to disable the onboard bluetooth and enable the dongle?