Can‘t remove app from app store connect!! Says there was an error.

I got the same error first. But then this worked for me:

1. Sign in to App Store Connect (appstoreconnect.apple.com) with your developer account.
2. Select "My Apps" from the top menu.
3. Choose the app you want to remove from the list of available apps.
4. Click on the "Pricing and Availability" tab.
5. In the "Availability" section, click on the "Edit" button next to "Territories."
6. Deselect all territories where the app is currently available. This will effectively remove the app from sale in all territories.
7. Click "Done" and then "Save" to confirm your changes.

When the processing is done (which can take a few minutes), the app will be be available in any territory and won't be searchable. Afterwards, when I go back to General -> Additional Information, I was able to remove it without errors

Hope this helps!

You can also click 'remove from sale' at the bottom of the "Pricing and Availability" tab. And once that's done I was able to remove the app in 'App Information'