I would like to know this as well. In contact form 7, if you select a file, then want to clear it out, how can you do that without refreshing the page?
Some forms are long, and refreshing is not a fun option. Perhaps there are a couple uploads that are optional, and you chose the wrong upload button; you are then stuck having to upload a file to that spot. You can either refresh the page and start over, you can chose a unacceptable file type and submit, forcing validation to take you back, or you can choose a junk file like a blank PDF.
A ‘Remove File’ button would be ideal, no?
Please let me know if this is a possibility in future updates.
Thanks!
Bob