Remove unwanted states from dropdown list in Magento - php

Question

I am new to magento and I am not able to make out how one can remove the unwanted states from dropdown list in magento. I tried to edit my below function as per this link http://doejo.com/blog/magento-how-to-remove-certain-states-from-state-region-list-at-checkout-or-registration/ but it did not work. Below i sthe code for removing unwanted states but when I add to my class in local folder, not getting any results.
$excludeRegions = array('AE','AA');
foreach ($collection as $region) {
if (!$region->getRegionId()) {
continue;
}
***//Here is the code from the link given
//BOF Custom Logic Here***
$regionCode = $region->getCode();
$this->_select->from(array('region'=>$this->_regionTable),
array('region_id'=>'region_id', 'country_id'=>'country_id', 'code'=>'code', 'default_name'=>'default_name')
)->where('code NOT IN (?)', $exclude_regions);
_getRegions function edited as per above code and link respectively.
protected function _getRegions($storeId)
{
$countryIds = array();
$countryCollection = $this->getCountryCollection()->loadByStore($storeId);
foreach ($countryCollection as $country) {
$countryIds[] = $country->getCountryId();
}
/** #var $regionModel Mage_Directory_Model_Region */
$regionModel = $this->_factory->getModel('directory/region');
/** #var $collection Mage_Directory_Model_Resource_Region_Collection */
$collection = $regionModel->getResourceCollection()
->addCountryFilter($countryIds)
->load();
$regions = array(
'config' => array(
'show_all_regions' => $this->getShowNonRequiredState(),
'regions_required' => $this->getCountriesWithStatesRequired()
)
);
$excludeRegions = array('AE','AA');
foreach ($collection as $region) {
if (!$region->getRegionId()) {
continue;
}
***//Here is the code from the link given
//BOF Custom Logic Here***
$regionCode = $region->getCode();
$this->_select->from(array('region'=>$this->_regionTable),
array('region_id'=>'region_id', 'country_id'=>'country_id', 'code'=>'code', 'default_name'=>'default_name')
)->where('code NOT IN (?)', $exclude_regions);
//EOF Custom Logic Here
$regions[$region->getCountryId()][$region->getRegionId()] = array(
'code' => $region->getCode(),
'name' => $this->__($region->getName())
);
}
return $regions;
}
After making the above changes, I tried below steps as my code is in /app/code/core/Mage/Directory/Helper/Data.php
Create a module Vids_Directory in pool local like app/code/local/Vids/Directory
Create app/etc/modules/Vids_Directory.xml
Create app/code/local/Vids/Directory/etc/config.xml
create app/code/local/Vids/Helper/Data.php