After you sign-up, GoCarma only collects data to confirm your occupancy in a registered vehicle.
You can opt out of this data collection at any time by doing any one of the following:
logging out of the GoCarma app
disabling Bluetooth on your phone
revoking the GoCarma app's permission to access Bluetooth
disabling Location Services on your phone
revoking the GoCarma app's permission to use Location Services
deleting the GoCarma app from your phone
Taking any one of those steps will result in the GoCarma app no longer reporting any data to GoCarma. You would need to undo this action if you wish to be detected in a vehicle.