I have a file input element like this:
<input name="fileupload[]" id="fileupload" type="file" multiple="" />
A user browses for their files and selects them, the files then appear in a list.
Now say a user wants to not add a particular file they hit a cancel button and it is deleted. That works but how do I remove the value from the fileupload input so that when they do upload the file that is meant to be deleted isn't added?
You could use javascript to place a hidden input with each separate file instead of holding them in an array initially, then attach an event handler onSubmit which could collect all the separate files and upload them.
When you need to delete a file from the 'queue' you could just use your javascript to remove the hidden input the same way you are removing it from the list.
If you'd like some code examples, please post some of your code to get us started - it is hard to post code for you if there is no indication of such things like which server side language you are using to handle the files and what javascript you are using to handle the client side code.
You cannot set the value(or clear the value) of a file-input, but you can replace the input with a new input, the effect would be the same.
