Starter disable info request

[Ursan]

I've been looking over the interwebs and this board for information to disable the starter. What I'm finding is how to disable the start/stop feature. That's now what I'm looking for.

Has anyone here installed or knows of a writeup for installing a starter kill switch?

I don't want a battery kill switch, just something that will disable the starter via a relay and a hidden switch.

Most kill switches I've seen lately disable the fuel pump. I'm not sure that's the best route as I'm thinking it'd throw a code.

I've done it on older (25+ years) cars, but this 2012 128i is a little different and I don't want to negatively affect the car.