Magento hide Callouts from every page in catalog.xml

To hide the Callout blocks from every page on your website, we are going to edit the following file:

\app\design\frontend\default\default\layout\catalog.xml

In this file the behaviour of various default blocks are handled.
To hide the Callouts we have to comment or delete the whole code block:

<block type="core/template"> ... </block>

Now you are all set. You may have to Flush Cache from Magento Admin.