It's pretty straightforward, yours is correct, just need to remove these 2 lines:
<record id="report_pos_order_pivot_extend" model="ir.ui.view">
<field name="name">report.pos.order.pivot.extend</field>
<field name="model">report.pos.order</field>
<field name="inherit_id" ref="point_of_sale.view_report_pos_order_pivot"/>
<field name="arch" type="xml">
<!-- <pivot string="Point of Sale Analysis" disable_linking="True">-->
<xpath expr="//field[@name='order_id']" position="after">
<field name="invoiced_target" type="measure"/>
</xpath>
<!-- </pivot>-->
</field>
</record>
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