The kill_application script that would have previously worked in this situation unfortunately does not work for Zebra devices under Android Enterprise management in SOTI.

For a moment I was thinking an alternative could be a shortcut to an mxconfig script that would kill the application for you but in looking at the MX options there doesn't seem to be a close application option.

An alternative to a script could be switching from the Activity Suppression based lockdown to the Native Kiosk and then enabling the Recents / App Switcher option so that you can give the user the access to kill the application manually themselves.

Note that access to the Recents button in the Native Kiosk is a function of Android 9 and higher so you would potentially have to upgrade your MC9300s to Android 10 in order to access this capability. I just tried it on an Android 8 TC52 (same Helios family as MC9300), and the Recents button was not shown on the lockdown of the device despite it being configured in the Profile. After upgrading the device to Android 10 the option appeared and I was able to manually close out apps while still in lockdown.