HttpClient client = new HttpClient();

                var request = new HttpRequestMessage
                {
                    Method = HttpMethod.Delete,
                    RequestUri = new Uri($"https://listing-external-sit.hepsiburada.com/Listings/merchantid/*******/sku/*******/merchantsku/*********"),
                    Headers =
                    {
                        { "authorization", "Basic *********************" },
                        {"User-Agent", "*************" }
                    },
                };

                using (var response = await client.SendAsync(request))
                {
                    response.EnsureSuccessStatusCode();
                    var body = await response.Content.ReadAsStringAsync();
                    MessageBox.Show(body);
                }

Even though I entered the required basic authorization and headers information on both sides, I get an error when I delete via Postman, but when I delete using C#, I get an unauthorized error.