How to remove x-powered-by header in .net core 2.0

public class SecurityHeadersMiddleware
{
    private readonly RequestDelegate next;

    public SecurityHeadersMiddleware(RequestDelegate next)
    {
        this.next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        context.Response.OnStarting(state =>
        {
            var ctx = (HttpContext)state;

            if (!ctx.Response.Headers.ContainsKey("Arr-Disable-Session-Affinity"))
            {
                ctx.Response.Headers.Add("Arr-Disable-Session-Affinity", "True"); // Disables the Azure ARRAffinity cookie
            }

            if (ctx.Response.Headers.ContainsKey("Server"))
            {
                ctx.Response.Headers.Remove("Server"); // For security reasons
            }

            if (ctx.Response.Headers.ContainsKey("x-powered-by") || ctx.Response.Headers.ContainsKey("X-Powered-By"))
            {
                ctx.Response.Headers.Remove("x-powered-by");
                ctx.Response.Headers.Remove("X-Powered-By");
            }

            if (!ctx.Response.Headers.ContainsKey("X-Frame-Options"))
            {
                ctx.Response.Headers.Add("X-Frame-Options", "DENY");
            }

            return Task.FromResult(0);
        }, context);

        await next(context);
    }
}

 var host = new WebHostBuilder()
        .UseKestrel(c => c.AddServerHeader = false)
        .UseContentRoot(Directory.GetCurrentDirectory())
        .UseIISIntegration()
        .UseStartup<Startup>()
        .Build();

WebHost.CreateDefaultBuilder(args)
               .UseKestrel(c => c.AddServerHeader = false)
               .UseStartup<Startup>()
               .Build();