A new feature has been introduced in Strategy Mobile 9.4.1 iOS Update 2 to allow users to log out of the Mobile app.
In order to use this feature, the setting Display log out option in action menu has to be enabled in the Mobile Configuration Settings. A new setting called Clear caches on log out has also been introduced and can also be enabled if needed. It is important to note that these settings are available starting in Strategy Mobile Server 9.4.1 Hotfix 3.

After that, the option should be visible in the Mobile app, as shown below:

In order to trigger the logout through URL API, use the following syntax:
mstr://?evt=4000