Hi Yue,
The Dataverse software (on deaccessioning) creates the tombstone page at the original Harvard URL. Even though the page looks different - it is now a tombstone page - the URL stayed the same. Note: The tombstone page is for a "Dataset".
The original DOI URL, which goes to DataCite, is resolved back to Harvard, the way it always did, same URL. But that Harvard URL now has tombstone content on it.
As I said, the Dataverse software takes care of creating the tombstone page in such a way that redirecting to a new URL (from Datacite) is not necessary.
--
Sherry