magento remove Product Type virtual product,bundle product and downloadable product.

app/code/core/mage/catalog/model/product/type.php

static public function getOptionArray()
    {
        $options = array();
        foreach(self::getTypes() as $typeId=>$type)
        {
            if($type['label'] != "Virtual Product" && $type["label"] != "Grouped Product" && $type["label"] != "Downloadable Product" && $type["label"] != "Bundle Product")
            {
                $options[$typeId] = Mage::helper('catalog')->__($type['label']);
            }
        }

        return $options;
    }