On standard package installation, Joomla displays some description on their footer in administrator page. In some versions, it says "Joomla is free software ...." and also display the version being used.
You can change/remove in some steps :
1. Go to
- /administrator/templates/(name of template being used)/login.php
- /administrator/templates/(name of template being used)/cpanel.php
- /administrator/templates/(name of template being used)/index.php
2. Open file and edit/remove the bottom code (on <div> footer </div>) then save it
* do it on each administrator templates
