how to hide this line from the acount.report_invoice

 <p t-if="o.type in ('out_invoice', 'in_refund')">
                        Please use the following communication for your payment : <b><span t-field="o.invoice_payment_ref"/></b>
                    </p>

i tried this xpath instruction but i can't trigger it, 

<xpath expr="//p[1]" position="replace"> 
 <p></p> 
</xpath> 

any suggestions ?