In sales.xml layout, there is sales_email_order_items which is responsible for order items and contains
<block type="sales/order_totals" name="order_totals" template="sales/order/totals.phtml">
<action method="setLabelProperties"><value>colspan="3" align="right" style="padding:3px 9px"</value></action>
<action method="setValueProperties"><value>align="right" style="padding:3px 9px"</value></action>
<block type="tax/sales_order_tax" name="tax" template="tax/order/tax.phtml">
<action method="setIsPlaneMode"><value>1</value></action>
</block>
</block>
Try to assign new template instead of sales/order/totals.phtml in order_totals and modify that new template to display only totals. I have not tested but this can give you direction.