See https://www-secure.symantec.com/connect/forums/open-files-workflow
The above seems to work but when I try to remove the files from the array it seem to work successfully but when I display the array the file is still there.
Either the selected file variable you are removing from the collection is incorrect or you're removing from the wrong collection or you are displaying the wrong collection. I've included a quick example of one way of doing it.
Attachment(s)