How to Hide the "Critical CSS For WP" Admin Menu

function plt_hide_critical_css_for_wp_menus() {
	//Hide the "Critical CSS For WP" menu.
	remove_menu_page('critical-css-for-wp');
}

add_action('admin_menu', 'plt_hide_critical_css_for_wp_menus', 11);

Where do I put this code?