How to Hide the "Dep. Minification" Admin Menu

function plt_hide_dependency_minification_menus() {
	//Hide the "Tools → Dep. Minification" menu.
	remove_submenu_page('tools.php', 'dependency-minification');
}

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

Where do I put this code?