In my experience with filePond when I try to delete a File:
if origin == "input"(1) it fires a DELETE request automatically to server.url but it doesn't include headers (specified in process.headers)
if origin == "local"(3) it doesn't fire any request and you have to do it by yourself manually
You have to add the headers to the server.revert end-point config.
If you want to allow your users to remove local server files you can implement the server.remove end-point.
Perfect. Now I'm able to delete files in the correct way. Thank you.