$ sequelize migration:create --name update-notes

'use strict';

module.exports = {
  up: (queryInterface, Sequelize) => {

    return queryInterface.addColumn(
      'Notes',
      'title',
      Sequelize.STRING
    );
  },

  down: (queryInterface, Sequelize) => {
   return queryInterface.removeColumn(
     'Notes',
     'title'
   );
  }
};

$ sequelize db:migrate

'use strict';
// models/notes.js
module.exports = (sequelize, DataTypes) => {
  const Notes = sequelize.define('Notes', {
    content: DataTypes.TEXT    // NO 'TITLE' COLUMN
  }, {});
  Notes.associate = function(models) {
    // associations can be defined here
  };
  return Notes;
};