Thanks Joe!
Just a note on my experience doing this today if it helps anyone reading or anyone on this Google team:
I deleted the relevant backends using the CLI which seemed to delete them, but returned an error `Error: Failed to delete backend:`
I looked in the Artifact Registry for any sub-folders in the
"firebaseapphosting-images" folder, but didn't see any sub-folders.
I no longer see the apps in the UI on Firebase and also no longer seeing the build for related App Hosting apps in GitHub.
This delete function feels like it should be in the Firebase UI, for Next.js developers used to using Vercel for deployment, having it in a UI would be most natural for these devs. Just an opinion
Great work on adding Next.js deployments on Firebase! :)