How to Hide the "Install Plugins" Admin Menu

function plt_hide_material_design_for_contact_form_7_menus() {
	//Hide the "Plugins → Install Plugins" menu.
	remove_submenu_page('plugins.php', 'tgmpa-install-plugins');
}

add_action('admin_menu', 'plt_hide_material_design_for_contact_form_7_menus', 1000000000);

Where do I put this code?