unset = async function (key) {
  var curr = await db.get(knex('dat_dns').where({key, isCurrent: 1}))
  if (curr) {
    await db.run(knex('dat_dns').update({isCurrent: 0}).where({key}))
    events.emit('updated', {key, name: undefined})
  }
}
@param {string} key
@returns {Promise<void>}