Hi Aseel,

Thank you for your support, currently I am working on Odoo 16 which we got recently updated from Odoo 15 version. 

I followed the steps given but I was unable to get the result is there anything different in Odoo 16?

Hi Aseel,
Follow the steps below

-You can edit the reports from Settings -> Technical -> Actions -> Reports.

-Select the report Quotation / Order and then click Qweb views. 

-Select a template you want to change. here as you mentioned if you want to remove the report

-Header and footer you have to select report_saleorder_document.

-Now you got the template, you can make any changes you need. If you need to remove header and  footer you can comment this line <t t-call="web.external_layout">  also don't forget to comment the closing tag of this t element in the last.

Regards