How can I dismiss the notification when I take the Screenshot?

I got a notification when I use the high-resolution screenshot. How can I disable it?

Because all notifications are managed by the Notification Manager, you can disable the notifications as follow:

#include "Framework/Notifications/NotificationManager.h" // In your header

FSlateNotificationManager::Get().SetAllowNotifications(false); // In your code

If used in New Editor Window (PIE), this code will disable notifications for the editor as well.