In includes/header.php change this
<td align="right" valign="bottom"><?php echo '<a href="' . tep_href_link(FILENAME_ACCOUNT, '', 'SSL') . '">' . tep_image(DIR_WS_IMAGES . 'header_account.gif', HEADER_TITLE_MY_ACCOUNT) . '</a> <a href="' . tep_href_link(FILENAME_SHOPPING_CART) . '">' . tep_image(DIR_WS_IMAGES . 'header_cart.gif', HEADER_TITLE_CART_CONTENTS) . '</a> <a href="' . tep_href_link(FILENAME_CHECKOUT_SHIPPING, '', 'SSL') . '">' . tep_image(DIR_WS_IMAGES . 'header_checkout.gif', HEADER_TITLE_CHECKOUT) . '</a>'; ?> </td>
to this
<td align="right" valign="bottom"><?php //echo '<a href="' . tep_href_link(FILENAME_ACCOUNT, '', 'SSL') . '">' . tep_image(DIR_WS_IMAGES . 'header_account.gif', HEADER_TITLE_MY_ACCOUNT) . '</a> <a href="' . tep_href_link(FILENAME_SHOPPING_CART) . '">' . tep_image(DIR_WS_IMAGES . 'header_cart.gif', HEADER_TITLE_CART_CONTENTS) . '</a> <a href="' . tep_href_link(FILENAME_CHECKOUT_SHIPPING, '', 'SSL') . '">' . tep_image(DIR_WS_IMAGES . 'header_checkout.gif', HEADER_TITLE_CHECKOUT) . '</a>'; ?> </td>
Commenting out the code to display the images.