The ASP FileUpload control can be handy if you are working with Web Forms as a means to easily integrate file uploading into your application and aren't experienced enough to work directly with HTML file inputs, Flash or jQuery based alternatives.
A very common use-case for the FileUpload control may be a simple application that allows a user to upload images or some other types of files and be able to see a thumbnail of the image after it has been uploaded, but has not yet been submitted or posted to the server.
// Hasta La Vista Files!
So how could you handle removing images that are already present within your Request.Files collection, just waiting to be uploaded? Well, here is a simple workaround to handle that.
This will now create a comma-delimited list that you can use to store all of the values of the files that you want to ensure are not uploaded.
Although this example was a very hasty one, there are many methods of handling this. You may want to seriously consider using one of the many jQuery based plug-ins that supports multiple file uploads or creating your own solution that uses a single file upload element for each file, which would allow you to manage them independently.