EN Odoo 18 la vista es 

mail_notification_light

Activate the developer mode.
Then go to setting. 
Open the technical tab : Views.
Open the "message_notification_email" view

Edit what you want to get the result you want.

As example : 
Remove completely the footer by commenting the last paragraph.

Hi, 

You can create an email template like this.

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
    <data noupdate="0">
        <record id="mail_template" model="mail.template">
            <field name="name">Email Template</field>
            <field name="model_id" ref="module.model"/>
            <field name="subject">Subject</field>
            <field name="email_to"></field>
            <field name="body_html" type="html">
                <table border="0" cellpadding="0" cellspacing="0"
                       style="padding-top: 16px; background-color: gray; font-family:Verdana, Arial,sans-serif; color: red; width: 100%; border-collapse:separate;">
                    <tr>
                        <td align="center">
                            <table border="0" cellpadding="0" cellspacing="0" width="590"
                                   style="padding: 16px; background-color: gray; color: red; border-collapse:separate;">
                                <tbody>
                                    <!-- HEADER -->
                                    <tr>
                                        <td align="center" style="min-width: 590px;">
                                        </td>
                                    </tr>
                                    <!-- CONTENT -->
                                    <tr>
                                        <td align="center" style="min-width: 590px;">
                                        </td>
                                    </tr>
                                    <!-- FOOTER -->
                                    <tr>
                                        <td align="center" style="min-width: 590px;">
                                        </td>
                                    </tr>
                                </tbody>
                            </table>
                        </td>
                    </tr>
                    <!-- POWERED BY -->
                    <tr>
                        <td align="center" style="min-width: 590px;">
                        </td>
                    </tr>
                </table>
            </field>
            <field name="lang">${object.lang}</field>
            <field name="auto_delete" eval="True"/>
            <field name="user_signature" eval="False"/>
        </record>
    </data>
</odoo>

Regards