This is my solution to use for my page.
First, unmerge, unbundling, un-minify js and CSS
Next, turn on Coverage tab in Chrome DevTools
https://developers.google.com/web/tools/chrome-devtools/coverage/
then check unused CSS and JS
or you can check each file one by one.
then you can remove a file unused, put code to the layout of the page you want to remove.
Ex: I will remove some file in the homepage so I put to cms_index_index.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<head>
<remove src="js/bundle/bundle0.js"/>
<remove src="css/bootstrap-magento.css"/>
</head>
</page>
Hope this solution will solve your issue.