code: def delete(self):
          
          api = self._client.instance_admin_api
          metadata = _metadata_with_prefix(self.name)
  
          api.delete_instance(self.name, metadata=metadata)
docs: Mark an instance and all of its databases for permanent deletion.
  
          See
          https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.DeleteInstance
  
          Immediately upon completion of the request:
  
          * Billing will cease for all of the instance's reserved resources.
  
          Soon afterward:
  
          * The instance and all databases within the instance will be deleteed.
            All data in the databases will be permanently deleted.