There is actually no need to log out of the SiriusXM app. When not in use, it will go into standby mode until you use it again. While in standby mode, the app will not use data minutes or drain your battery. Best of all, the SiriusXM app will always be ready for you when you select it (no need to enter your username and password each time).
To put the SiriusXM app into standby mode:
1. Pause the app.
2. Press the device home button to put the app into standby mode.