Add / delete custom options to simple products programatically in Magento

Example:

 $products = Mage::getModel('catalog/product')->getCollection(); //todo: add your filters here

        //custom options to be added
        $newCustomOptions = array(
            array(
                'title' => 'Name',
                'type' => 'field',
                'is_require' => 1,
                'sort_order' => 0,
                'max_characters' => 255,
                'values' => array()
            ),
            array(
                'title' => 'Email',
                'type' => 'field',
                'is_require' => 1,
                'sort_order' => 1,
                'max_characters' => 255,
                'values' => array()
            ),
        );

        foreach($products as $product) {
            $currentCustomOptions = $product->getProductOptionsCollection();

            //delete current custom options
            if($currentCustomOptions->getSize() != 0) {
                foreach ($currentCustomOptions as $option) {
                    $option->delete();
                }
                $product->setHasOptions(0);
                $product->save();
            }

            Mage::getSingleton('catalog/product_option')->unsetOptions();

            //add new custom options
            $product->setProductOptions($options);
            $product->setCanSaveCustomOptions(true);
            $product->save();            
        }