Goldman Sachs demands Google delete one of its e-mails

Reuters:

Goldman Sachs Group Inc said a contractor emailed confidential client data to a stranger’s Gmail account by mistake, and the bank has asked a U.S. judge to order Google Inc to delete the email to avert a “needless and massive” breach of privacy.

This raises some questions. Who owns a specific piece of email? Who has the right to delete it? Is it owned by the sender? The recipient? Google?