zentao/extension/lite/product/ext/config/lite.php

<?php
unset($config->product->search['fields']['stage']);
unset($config->product->search['fields']['product']);
unset($config->product->search['fields']['plan']);
unset($config->product->search['fields']['source']);
unset($config->product->search['fields']['sourceNote']);
unset($config->product->search['fields']['fromBug']);