https://book.cakephp.org/3.0/en/phinx/migrations.html#working-with-columns

<?php

require('vendor/autoload.php');

use Schema\Wrapper as Wrapper;

$pdo = new \PDO('sqlite:database.sqlite3');

Wrapper::set_driver($pdo);
Wrapper::begin();

$table = Wrapper::get_table('Coisa');

$table->addColumn('ida','integer');
$table->addColumn('idb','integer');

$table->removeColumn('idb');

$table->save();
Wrapper::commit();