You might want to look at just pulling the sim card (assuming its physical).
For long term (meaning transfer of vehicle) you might want to buy a second head unit. When you sell the car have it swapped out so none of your history is in it. Because even if you remove the sim it will still collect data, just not be able to send it back home.
There's a lot of variables in threat model and budget though so I just mention these as options, not necessarily recommendations.