Hi,
In app/etc/modules folder.
You will have a Mage_All.xml file that contains the bulk of the Magento core module declarations.
Look for the Mage_Rss section and change the tag to <active>false</active>,
       
<Mage_Rss>
        <active>true</active>
        <codePool>core</codePool>
         <depends>
            <Mage_Catalog/>
            <Mage_CatalogInventory/>
            <Mage_Sales/>
            <Mage_SalesRule/>
            <Mage_Wishlist/>
         </depends>
    </Mage_Rss>
Thanks
Jigneshkumar
iFour Technolab Pvt. Ltd.