Remove orders via batch by condition.
<?php
$order_ids = db_select('commerce_order', 'n')
->fields('n', array('order_id'))
->condition('n.created', 1439337600, '>=')
->execute()
->fetchCol();
foreach ($order_ids as $order_id) {
$operations[] = array('commerce_order_delete', array($order_id));
}
$batch = array(
'title' => t('Deleting'),
'operations' => $operations
);
batch_set($batch);