How to remove "Powered by MediaWiki" from the footer in MediaWiki
By default, the footer of your MediaWiki site displays an image with the words Powered by MediaWiki. If you want to remove it, you can do this by inserting a line in the LocalSettings.php file of your MediaWiki.
On a new line at the end the the file put the following:
unset( $wgFooterIcons['poweredby'] );
Note that the above will work for MediaWiki versions 1.17 and newer.
The LocalSettings.php file that you have to modify to achieve this is in the root MediaWiki folder on your MediaWiki hosting account. If, for instance, the application is installed in the public_html directory on your account (making the URL of the frontend yourdomain.com), then the path to the file on the account will be public_html/LocalSettings.php. HostKnox customers can edit files on their accounts from the File manager of the Pixie control panel. It can also be done by downloading the file on your local computer, editing it with a text editor (e.g. Notepad) and uploading it back.
Here are some other articles about modifications to the footer that you may find useful: