How do I remove the manufacturer from the product slug/url?

The manufacturer name is automatically prepended to the product slug (its URL). If you wish for this to not happen you can set the static Aero\Catalog\Models\Product::$slugContainsManufacturer boolean to false.

<?php

namespace Acme\MyModule;

use Aero\Catalog\Models\Product;
use Aero\Common\Providers\ModuleServiceProvider;

class ServiceProvider extends ModuleServiceProvider
{
   public function setup()
   {
       Product::$slugContainsManufacturer = false;
   }
}