How to close an app hands free with siri

Is this app actually running? If not there is no reason to "close" it which actually just removes it from the recently used list and is not needed.

You can open apps via Siri but you can't close apps. Siri will give instructions on how to close an app but will not close it for you.

What app are you referring to?

If they are playing media at the time you say either "Hey Siri, pause" or "Hey Siri, stop".