In Prestashop 8.1.0 I edited the ps_shoppingcart.tpl and/or cart-summary-totals.tpl.
I commented out the lines:
{* <div class="cart-summary-line cart-total">
<span class="label">{$cart.totals.total_including_tax.label}</span>
<span class="value">{$cart.totals.total_including_tax.value}</span>
</div>
*}