Go through the following steps:
1. First things first, you can only delete a folder if it is empty. So make sure that the folder in question has been emptied in the back-end.
2. Refresh your app by holding and dragging the content of the app down with one finger and then release. This should refresh the view you are currently seeing.
3. Check if there is an update available for your app. If that is the case, update it.
If none of the steps above make the folder disappear, contact our support team at email@example.com or via the blue chat icon in the lower right corner of the screen, which is available both here on the website and in your Napp® CMS.