JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
To delete files on your file upload field in your forms, you'll need to delete the submission itself.
Please note that deleting submissions is irreversible, it will permanently remove it in our servers without any backup. I strongly advise downloading all your submissions and file uploads so that you have a backup for future references.
Here's a guide on how to view and delete your submissions: https://www.jotform.com/help/269-How-to-view-Submissions
Let us know if you need more information on this.