One popular think how to remove or customization the WordPress admin panel footer text that appear.
Here i am teaching you how to do that, you don’t have need much struggle just add this code into your function.php file and you can remove or change the footer text:

add_filter('admin_footer_text', 'remove_footer_admin'); //change admin footer text
function remove_footer_admin ()
{
    echo "Here is your new copyright test to replace the old WordPress footer text";
}