Deletes a secret.
This method deletes the secret specified by SecretName. If there are multiple versions of the secret, all of them are deleted.
Note that the secret is only soft-deleted; it can be recovered during the retention period using the RecoverSecret method, or permanently deleted using the PurgeSecret method. The length of the retention period depends on the configuration of the currently-selected Vault, refer to the Azure Key Vault documentation for more information.