import { buildClient } from '@datocms/cma-client-node';
async function run() {
  const client = buildClient({ apiToken: '<YOUR_API_TOKEN>' });
  
  const itemId = '34';
  
  const scheduledUnpublishing = await client.scheduledUnpublishing.create(itemId, {
    unpublishing_scheduled_at: '2017-02-10T11:03:42.208Z'
  });
  
  console.log(scheduledUnpublishing);
}
run();

{
  id: '34',
  unpublishing_scheduled_at: '2017-02-10T11:03:42.208Z',
  item: {
    type: 'item',
    id: '4235'
  }
}