Add this to functions.php and all users who are not administrators and try to access the admin panel will be redirected to the homepage URL. Good way of keeping members away from anything WordPress on your site.
Code Snippet:
function restrict_admin_access(){
global $current_user;
get_currentuserinfo();
if (!array_key_exists('administrator', $current_user->caps)) {
wp_redirect( get_bloginfo('url') );
exit;
}
}
add_action('admin_init', 'restrict_admin_access', 1);