Hi,

1- Activate Developer Mode:

               - Go to the Settings app.

               - Scroll down and click on Activate the developer mode at the bottom of the page.

2- Navigate to Reports:

                - Go to the Settings app again.

                - Under the Technical section (visible in developer mode), select User Interface > Views.

3 - Search for the Invoice Report Template:

                 - In the search bar, look for report_invoice_document.

                 - This is the default template for invoices.

4- Edit the Template:

                  - Open the report_invoice_document template.

                  - Find the section of the code that includes the "Powered by Odoo" line. It is usually located towards the bottom of the template in a or tag with text similar to Powered by https://www.odoo.com">Odoo.  

                   - You can either remove this line completely or comment it out using HTML comment tags .

                   * Save the Changes:

                              After editing the template, click Save to apply the changes.

                   * Test the Changes:

                              Generate a new invoice and check the footer to ensure that the "Powered by Odoo" text has been removed.

Please take a look at the following solved forum.

https://www.odoo.com/sl_SI/forum/pomoc-1/how-do-i-turn-off-the-powered-by-odoo-text-in-the-footer-of-a-website-199187

Hope it helps

Please try this code

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

<templates id="template" xml:space="preserve">

    <t t-name="ctm_posreceipt.OrderReceipt" t-inherit="point_of_sale.OrderReceipt" t-inherit-mode="extension">

        <xpath expr="//p" position="replace">

            <p></p>

        </xpath>

    </t>

</templates>