Lets have the category image delete button displayed if there is category image is available:

Change Step 3 with following changes:

Find:
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$contents[] = array('text' => '
' . tep_info_image($cInfo->categories_image, $cInfo->categories_name, HEADING_IMAGE_WIDTH, HEADING_IMAGE_HEIGHT) . '
' . $cInfo->categories_image);

Add following under it:
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if ($cInfo->categories_image) $contents[] = array('text' =>'
' . tep_image_button('button_delete_image.gif', IMAGE_DELETE) . '');

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Finally, don't forget to produce and add "button_delete_image.gif" in your /catalog/admin/includes/languages/[YOUR_LANGUAGE]/images/buttons folder

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