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There should be a line of code in public_html/app/design/frontend/default/your_template/template/page/homepage.phtml:
<h1>Follow us on Twitter</h1>
<?php echo $this->getLayout()->createBlock('cms/block')->setBlockId('twitter')->toHtml() ?>
You'll want to comment out the twitter code but leave the col2 div if you have one, or else you'll have to play with template css to adjust the width of other columns.