The "Country of Manufacture" is one of Magento's default product attribute which you can choose not to display on the frontend layered navigation.
Follow the below steps to hide it from the frontend.
Go to Catalog -> Attributes -> Manage Attributes.
Search for "country_of_manufacture" in the Attribute Code column.
Open the attribute detail page and in the Frontend Properties, choose NO in "Use In Layered Navigation".
Save the attribute, clear indexes and cache.
Now, the attribute won't be displayed anymore on the frontend.