If you wanted to remove with CSS (meaning the reference would still appear in the page source, but not appear in the browser), you could add the following CSS to a child theme:
#footer .credit_inside {
visibility: hidden;
}If you want to remove completely from the page source, you would need to track down the function bandana_footer() action hook and then write an appropriate function in a child theme to replace that bandana_footer(). For more information on child themes, please review: Child_Themes