There have been some experimentation but the best (IMO) option is hitting the SOS button to call and navigating the phone menu to get to a representative, not emergency services and having them disconnect your car. You may need your VIN, you’ll need to confirm that you do not want connected services and it may take a day or so to take effect. Now, my SOS button doesn’t have the green light and while the radio - according to the infotainment - is still powered, it is no longer connected to the network.

Another way if you don’t plan on using the microphone (like for calls) you can pull the DCM fuse but I prefer the above option.