Deletes a client-side encryption identity. The authenticated user can no longer use the identity to send encrypted messages. You cannot restore the identity after you delete it. Instead, use the CreateCseIdentity method to create another identity with the same configuration. For administrators managing identities and keypairs for users in their organization, requests require authorization with a service account that has domain-wide delegation authority to impersonate users with the https://www.googleapis.com/auth/gmail.settings.basic scope. For users managing their own identities and keypairs, requests require hardware key encryption turned on and configured.