Detach a domain from a revision

Remove this revision's binding for the given hostname. Hostnames are unique, so the binding is identified by hostname alone — the timeline/context is inferred. Pass the same hostname (including any {variable} template syntax) that was used to attach it.

Passing a default-alias template detaches the revision from the app's default managed domain instead of removing a custom binding: the default production host rolls back to the next most recently attached revision, and the default preview host for this revision goes offline.

Detaching one hostname leaves the revision's other hostnames untouched, even when they share a parent domain. Other revisions and app-level custom-domain assignments are not affected. Returns 404 if no binding exists.