"create a variable called id"
var id
"then inside your client message statement change id ->  id = message.id"
client.on('message', message => {
  id = message.id
});
"inside your command type  message.fetch(id).then(msg => msg.delete());"
  if (message.content === !test)
      message.fetch(id).then(msg => msg.delete());      
}});