You can use below code for hide some part in qweb report.
Here, I want to hide tax table and Changed string value and also hide payment term of Inovice report.
<?xml version="1.0" encoding="utf-8"?>
<odoo>
<data>
<template id="report_invoice_document_inherit" inherit_id="account.report_invoice_documnet">
<!-- Changed 'Draft Invoice' to 'Tax Invoice' and 'Invoice' to 'Tax Invoice'-->
<xpath expr="//div[@class='page']/h2/span[1]" position="replace">
<span t-if="o.type == 'out_invoice' and (o.state in ('draft', 'open', 'paid'))">Tax Invoice</span>
</xpath>
<!-- Hide span -->
<xpath expr="//div[@class='page']/h2/span[3]" position="replace"/>
<!--Hide Tax table -->
<xpath expr="//div[@class='page']/div[4]" position="attributes">
<attribute name="class">hidden</attribute>
</xpath>
<!-- Hide payment term value from invoice report -->
<xpath expr="//div[@class='page']/p[2]" position="attributes">
<attribute name="class">hidden</attribute>
</xpath>
</template>
</data>
</odoo>
Hope above code help you.
Best Thanks,
Ankit H Gandhi.