The question you posted over in the developer area seemingly didn’t clearly mention that it was a developer subscription you were seeking to identify and delete, and were having issues finding. I suspect that confusion is why you were sent over here.
If you can log into the Apple developer portal via the Account tab in the upper right of that webpage, and if you can see the Apple Developer subscription associated with your Apple Account via the App Store app’s list of Subscriptions info, then you are using an Apple Account with developer access.
If you cannot, then you’re not enrolled with that Apple Account.
Here is how to contact Developer Support directly: https://developer.apple.com/contact/
Once you do find the Apple Account enrolled and unenroll it, apps associated with that developer account will cease to work. The Apple Developer program does have a means to transfer apps, if those are intended to continue to be available.