HI, Please Try following code:-

<template id="website.layout_footer_copyright" inherit_id="website.layout" name="Footer Copyright">
 <xpath expr="//footer" position="inside">
  <div class="container mt16 mb8">
  <div class="pull-right" t-ignore="true" t-if="not editable">
   <!-- Powered by <a class="label label-danger" href="Company_link">YourCompanyName</a>. this is optional,you can remove this line or simply give your company name-->
  </div> 
  <div class="pull-left text-muted"> 
  Copyright &amp;copy; <span t-field="res_company.name">Company name</span>
  </div>
  </div>
 </xpath>
 </template>

It appears to be defined at the following location:

./addons/web/views/webclient_templates.xml, lines 315-7

<div class="o_sub_menu_footer">
    Powered by <a href="http://www.odoo.com" target="_blank"><span>Steam</span></a>
</div>

OK, it didn't say "Steam" before, that was me just checking it out. I guess rather than just removing those three lines from the "web.menu_secondary" template, it would be better to override it in your own code.

That is being done once you are a customer of Odoo and have purchased customization pack.