Cancel a notification (created by Tasker) currently in the System Notification bar.
Title is the title of the notification to cancel. If Title is not specified, all notifications will be cancelled (including 'permanent') ones.
If more than one notification with the specified Title is currently being displayed, only the last one displayed will be cancelled, the otherwise will need to be cancelled manually.
Warn Not Exist: if set, a warning will be flashed if there is no matching notification.