How to Hide ActiveCampaign Email Preference Center Admin Menus

function plt_hide_pramadillo_activecampaign_email_preference_center_menus() {
	//Hide the "Settings → ActiveCampaign Preference Center" menu.
	remove_submenu_page('options-general.php', 'activecampaign-preference-center');
	//Hide the "Settings → Upgrade" menu.
	remove_submenu_page('options-general.php', 'activecampaign-preference-center-pricing');
}

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

Where do I put this code?