You can't delete file attachments from the PDF using Reader when they are added via the attachments panel. That's not one of the editing functions that Reader can perform.
However, file attachments can be added as annotations attached to a particular page. You can delete these because they are annotations. You won't need a dialog to delete them either, you can just select the annotation and delete it.
Thank you for the help.
Would it be possible to do if I were requested to create three buttons that would allow users to attach files as annotations, view them in a separate window, and delete them? If so, any suggestions on resources I can use to accomplish the tasks?
Why spend a lot of time and effort on creating something that already exists and is easy to use? The file attachment annotations can be viewed (and edited) in both the Comment panel and the Attachments panel... There's really no need to create another panel to do so using a script.