Removing Logo/Special Fonts

If you mean the icon, there is an option in theme options to remove it. To add a custom logo you would have to modify the header.php file in a child theme and add your logo there.

For the fonts you use this code in functions.php in a child theme:

//remove existing fonts
function custom_deregister_fonts() {
  wp_deregister_style('google_fonts');
}
add_action('wp_enqueue_scripts','custom_deregister_fonts',100); 

// Setup  New Google fonts
    function load_fonts() {
            wp_register_style('customeFonts', 'http://fonts.googleapis.com/css?family=your_fonts_here');
            wp_enqueue_style( 'customeFonts');

		}

    add_action('wp_print_styles', 'load_fonts');