cooperative-market/website_portal_restrict_modification/views/portal_website_templates.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright 2018 Rémy Taymans <remytaymans@gmail.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
-->
<odoo>

    <!-- Modifying the form -->
    <template id="website_portal_restrict_my_details"
              name="Website Portal Restrict Modification"
              inherit_id="portal.portal_my_details">
        <xpath expr="//input[@name='name']/.." position="before">
            <div class="col-lg-12">
                <div class="alert alert-info">
                    <strong>Info !</strong>
                    To modify information that cannot be edited in this form,
                    please contact us.
                </div>
            </div>
        </xpath>
        <xpath expr="//input[@name='name']" position="attributes">
            <attribute name="t-att-readonly">True</attribute>
        </xpath>
        <xpath expr="//input[@name='email']" position="attributes">
            <attribute name="t-att-readonly">True</attribute>
        </xpath>
        <xpath expr="//input[@name='company_name']" position="attributes">
            <attribute name="t-att-readonly">True</attribute>
        </xpath>
        <xpath expr="//input[@name='vat']" position="attributes">
            <attribute name="t-att-readonly">True</attribute>
        </xpath>
    </template>

</odoo>