To remove joomla logo that shows on Offline when you put your site offline follow these simple steps:
Login into your cpanel
Click on file manager when it opens,
Click public_html when it opens
Click on the directory you install your joomla, if joomla in the root, ignore this and move to the next.
Click on template> System, when it opens
You will see "offline" template, right click it and click edit, when it opens
In the files look for this line: <img src="images/joomla_logo_black.jpg" alt="Joomla! Logo" />
and remove it, after that click Save. That is all.
Go to your home it won't be there anymore.
