@Rob: The sample app doesn’t demonstrate this functionality.
I guess I need to describe the problem a bit better.
The app I am working on is a turn based game that sends a lot of push messages. When a push message arrives on the device it is shown in a list in the operating systems notification center. (Android version shown on screenshot)

Since we are sending a lot of messages we want to be able to clear the entries coming from our app, when the app is opened. Otherwise the user will end up having hundreds or thousands of messages there… which is very annoying.
The documentation for (plugin.notifications.v2) notifications.cancelNotification() says:
Removes the specified notification (or all notifications) from the scheduler, status bar, and/or notification center.
(…) If no ID is passed, all notifications are cancelled.
We have it working on iOS but on Android notifications.cancelNotification() doesn’t clear the messages in the notification center (for some strange reason local notifications are cleared, so to test this you need to set up remote push)
Thanks