Unless otherwise indicated, the code snippets you see below should be placed into your theme’s functions.php file.
Here is the code needed to remove the Google AdSense metabox from the Genesis Theme Settings screen:
// Remove AdSense metabox from Theme Settings.
add_action( 'genesis_theme_settings_metaboxes', 'child_remove_adsense_metabox' );
function child_remove_adsense_metabox() {
remove_meta_box( 'genesis-theme-settings-adsense', 'toplevel_page_genesis', 'main' );
}