server-tools/mass_mailing_enterprise_remove/views/res_config_view.xml

<?xml version="1.0" encoding="utf-8"?>

<!--
    Copyright 2016 LasLabs Inc.
    License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
-->

<odoo>

    <record id="view_mass_mailing_configuration" model="ir.ui.view">
        <field name="name">Configure Mass Mailing</field>
        <field name="model">mass.mailing.config.settings</field>
        <field name="inherit_id" ref="mass_mailing.view_mass_mailing_configuration"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='module_mass_mailing_themes']" position="attributes">
                <attribute name="invisible">True</attribute>
            </xpath>
        </field>
    </record>

</odoo>