How to Hide Coupon X Discount Pop Up Admin Menus

function plt_hide_coupon_x_discount_pop_up_menus() {
	//Hide "Coupon X".
	remove_menu_page('couponx');
	//Hide "Coupon X → Dashboard".
	remove_submenu_page('couponx', 'couponx');
	//Hide "Coupon X → Create New Widget".
	remove_submenu_page('couponx', 'add_couponx');
	//Hide "Coupon X → Leads".
	remove_submenu_page('couponx', 'leads_list');
	//Hide "Coupon X → Integrations".
	remove_submenu_page('couponx', 'cx_integrations');
	//Hide "Coupon X → Recommended Plugins".
	remove_submenu_page('couponx', 'cx-recommended-plugins');
	//Hide "Coupon X → Upgrade to Pro".
	remove_submenu_page('couponx', 'couponx_pricing_tbl');
}

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

Where do I put this code?