With Microsoft Intune you can configure each app as being removable or not by the user. We sometimes assign an app to devices that we are OK with the user removing if they decide they would prefer not to use it. However in other cases we want to ensure it is not possible for the user to remove an app. I asked your support team if there was an option for doing this within SimpleMDM and they were able to determine how Intune accomplishes it and asked that I post my request here. The response from your support agent is below:

I was able to figure out how Intune is able to control whether or not individual apps are allowed to be removed or not. It turns out there is a property that can be passed when installing an app via MDM that flags apps as removable/unremovable. If you'd like to see this implemented within SimpleMDM, I'd recommend that you submit the idea to our Suggestions portal