How to enable "Use Default Value" for product attribute programmatically?

Did somebody know how can I enable programmatically "Use Default Value" for a product attribute in second StoreView so that Magento uses the value from the default StoreView?

I tried following code b开发者_JAVA百科ut this doesn´t work:

$soap->call($sessionId, 'product.update', array($sku, array('color_addition'=>''), 'gb'));

You can enable "Use Default Values" for the attribute value by passing false.

$soap->call($sessionId, 'product.update', 
array($sku, array('color_addition'=>false), 'gb'));