ct.cs

// reference commercetools.NET.SDK via nuget

using System;
using System.Threading.Tasks;
using commercetools.Categories;
using commercetools.Common;
using commercetools.ProductProjections;
using commercetools.ProductProjectionSearch;
using commercetools.Products;
using commercetools.Products.UpdateActions;

namespace ctdeleteallproducts
{
    class Program
    {
        static async Task Main(string[] args)
        {
            IClient client = new Client(new Configuration()
            {
                OAuthUrl = "https://auth.sphere.io/oauth/token",
                ApiUrl = "https://api.sphere.io",
                ClientID = "client_id_here",
                ClientSecret = "client_secret_here",
                ProjectKey = "project_key_here"
            });

            var categoriesResponse = await client.Categories().QueryCategoriesAsync(limit: 500);

            var categories = categoriesResponse.Result;

            foreach (var category in categories.Results)
            {
                await client.Categories().DeleteCategoryAsync(category);
            }
            
            Response<ProductProjectionQueryResult> result = await client.ProductProjectionSearch()
                .SearchProductProjectionsAsync();

            var productsResponse = await client.Products().QueryProductsAsync(limit: 500);

            if(!productsResponse.Success)
            {
                return;
            }

            var products = productsResponse.Result;

            foreach (var product in products.Results)
            {
                var unpublishResult = await client.Products().UpdateProductAsync(product, new UnpublishAction());

                var unpublishedProduct = await client.Products().GetProductByIdAsync(product.Id);

                var ya = await client.Products().DeleteProductAsync(unpublishedProduct.Result);
            }
        }
    }
}