Since iTunes connect policy has been changed, If your app is not approved yet, you can't delete the app. Even if you upload your binary and then reject it, it will remains there. The only way delete an app from iTunes Connect it has to be approved once.
From Apple:
Deleting an App
If you’ve created an app in iTunes Connect that you no longer need to
manage, you can delete it from iTunes Connect.
Apps can’t be deleted if they are part of a Game Center group or
currently displayed on a store. You’ll want to remove the app from
sale or from the group if you want to delete it. See “Removing an App
from Sale” or “Removing an App from a Group” in Game Center
Configuration Guide for iTunes Connect. Apps that have not been
approved yet can’t be deleted; instead, reject the app. See “Rejecting
Your Binary.”
You can see more details at Transferring And Deleting Apps