You have two options here, with two different and important distinctions.
1) Simply delete your app
If you choose this option you'll lose any users/installs you've acquired, and you'll also have to name your new app something slightly different than the original
2) Transfer your app to the DWNLD developer account
The iOS App Store allows you to transfer your app to another developer account. This one you maintain your users/installs and can keep your app name as is. We'll simply overwrite your current app with your new DWNLD app.
For instructions, see here.
Please contact us (email@example.com) when you are transferring so we can provide our developer ID numbers.