The slow way that works:
Mage::getModel('catalog/product')
->load($productId)
->setStoreId($storeId)
->setData($code , null)
->save();
I've seen:
Mage::getModel('catalog/product')
->addAttributeUpdate($code, null , $storeId);
This however deletes the default value as well. (possible bug ?)
Other examples I have seen are raw mysql delete queries.
I though that this would be something native to Magento.
Any thoughts on this?