https://youtu.be/8aNTIxa-qRE

I'm open to suggestions but I think the best solution would be to add a field to the website module.

from odoo import models, fields

class WebsiteInherited(models.Model)
    _inherit = 'website'
    no_footer = fields.Boolean(string='Website Footer', default=False)

Then create an xpath to the footer

<template id="footer_custom" inherit_id="website.footer_custom" name="Footer">
    <xpath expr="//div[@id='footer']" position="attributes">
        <attribute name="t-if">not request.website_id.no_footer</attribute>
    </xpath>
</template>

Untested but I assume something like that.

Edit:

I forgot to mention you'll have to add the no_footer to the website view so you'll be able to change the value