1. get a _real_, unabridged service manual. that takes some darkweb experience nowadays.
2. identify anything that looks like capable of housing a cell modem. that takes some understanding of contemporary car electronics
3. deny RF interface to units identified. that takes some understanding what RF = radio frequency interface is and also getting rid of fear of disassembling significant portions of your car.
All in all that is a great learning experience.
If I disable the modem, does that disable the SOS feature? Do I need to tell my insurance company?