Users can delete previously uploaded files using the following steps:
- After uploading files, find the Delete button located on the table displaying uploaded files.
- Next to the uploaded files, there will be checkboxes. Check the box next to the uploaded file you want to delete.
- Click on the Delete button.
- A confirmation popup will appear, asking you to confirm the deletion.
- Click the "OK" button in the confirmation popup to confirm the deletion.
Upon successful deletion of the files, a success message will appear on the screen, and the files deleted from the records. 
PS: View Mass File Upload, Salesforce file upload app, on Salesforce AppExchange:
https://appexchange.salesforce.com/appxListingDetail?listingId=82cf236b-1ee8-4ea7-aebf-fd0c89fb93bd