Deletes a client-side encryption key pair permanently and immediately. You can only permanently delete key pairs that have been turned off for more than 30 days. To turn off a key pair, use the DisableCseKeyPair method. Gmail can't restore or decrypt any messages that were encrypted by an obliterated key. Authenticated users and Google Workspace administrators lose access to reading the encrypted messages. 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.