Hii,

Use t-if + group check

To fully  remove the button for internal users please try below code:

<template id="cw_sale_order_portal_content_inherit" inherit_id="sale.sale_order_portal_content">

  <xpath expr="//span[@id='shipping_address']/h5" position="replace">

    <h5 class="mb-1">Delivery Address</h5>

  </xpath>

  <xpath expr="//a[contains(normalize-space(text()), 'Accept & Sign')]" position="replace">

    <t t-if="not request.env.user.has_group('base.group_user')">

      <a href="/my/orders/accept" class="btn btn-primary">Accept & Sign</a>

    </t>

  </xpath>

</template>

base.group_user → This is the internal user group.

So not request.env.user.has_group('base.group_user') means: show this only to non-internal users → portal or public .

i hope it is use full