Is it possible to set an application to be managed only by the Tenant and not by Venue Managers?

Yes, it is possible.

In order to set the Tenant level as the only level able to manage an application, it is necessary to perform the following steps:

1. Open the Venue menu in the quick access toolbar and then click the appropriate Venue
   
   
   
   
2. Enter the Apps tab.
   

   

   
   
3. Select the status for the desired application and turn this into Disabled.