muk_web/muk_web_report_page/template/minimal_layout.xml

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

<!--

    Copyright (c) 2017-2019 MuK IT GmbH.

    This file is part of MuK Report Page 
    (see https://mukit.at).

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.

  -->

<odoo>

<template id="minimal_layout" name="Report Layout" inherit_id="web.minimal_layout">
	<xpath expr="//body/t[@t-raw='body']" position="after">
		<script>
			function checkPagenumbers() {
				var topages = document.getElementsByClassName("topage");
			  	Array.prototype.forEach.call(topages, function(topage) {
					if(topage.innerHTML == 1) {
						topage.parentElement.style.display = "none"; 
					}
				});
			}
			var prev_handler = window.onload;
			window.onload = function() {
				if (typeof prev_handler === 'function') { 
					prev_handler();
				}
				checkPagenumbers();
			};
		</script>
	</xpath>
</template>

</odoo>