I have an app that I would like to delete. However, using the docs, there is no "Delete App" button even though my app has the "right" status of "Prepare for Submission".
As it says below in the docs...
The app status can be one of the following, assuming that there is at least one approved version of the app [...]
...your application must have been approved for at least one time. I guess this is your issue.
Hope that helps :)