The default template that comes with the script has a powered by text, including a backlink to our website. You are free to leave or remove it from your installation. If you would like to remove that default powered by text as well as backlink, then:

OPEN:

/templates/default/layouts/core.tpl

FIND & REMOVE THE LINE STARTING WITH:

{$lang.footer.powered_by}

Now, clear your cache from Admin Panel, which can be found under Utilities.