How to Hide theMarketer - Email marketing, Newsletters, Automation & Loyalty for Woocommerce Admin Menus

function plt_hide_themarketer_menus() {
	//Hide the "TheMarketer" menu.
	remove_menu_page('mktr');
	//Hide the "TheMarketer → Start Onboarding" menu.
	remove_submenu_page('mktr', 'mktr_tracker');
}

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

Where do I put this code?