How to Hide Subscribe to Category Admin Menus

function plt_hide_subscribe_to_category_menus() {
	//Hide "STC Subscribe".
	remove_menu_page('stc-subscribe-settings');
	//Hide "STC Subscribe → Settings".
	remove_submenu_page('stc-subscribe-settings', 'stc-subscribe-settings');
	//Hide "STC Subscribe → Notifications".
	remove_submenu_page('stc-subscribe-settings', 'edit.php?post_type=notifications');
	//Hide "STC Subscribe → Subscribers".
	remove_submenu_page('stc-subscribe-settings', 'edit.php?post_type=stc');
}

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

Where do I put this code?