How to Hide Support Ticket System By Phoeniixx Admin Menus

function plt_hide_support_ticket_system_by_phoeniixx_menus() {
	//Hide the "Ticket System" menu.
	remove_menu_page('phoen_ticket_system');
	//Hide the "Ticket System → Settings" menu.
	remove_submenu_page('phoen_ticket_system', 'phoen_ticket_settings');
}

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

Where do I put this code?