How do I remove a file from the FileList

If you want to delete only several of the selected files: you can't. The File API Working Draft you linked to contains a note:

The HTMLInputElement interface [HTML5] has a readonly FileList attribute, […]
[emphasis mine]

Reading a bit of the HTML 5 Working Draft, I came across the Common input element APIs. It appears you can delete the entire file list by setting the value property of the input object to an empty string, like:

document.getElementById('multifile').value = "";

BTW, the article Using files from web applications might also be of interest.

This question has already been marked answered, but I'd like to share some information that might help others with using FileList.

It would be convenient to treat a FileList as an array, but methods like sort, shift, pop, and slice don't work. As others have suggested, you can copy the FileList to an array. However, rather than using a loop, there's a simple one line solution to handle this conversion.

 // fileDialog.files is a FileList  var fileBuffer=[]; // append the file list to an array Array.prototype.push.apply( fileBuffer, fileDialog.files ); // <-- here // And now you may manipulated the result as required // shift an item off the array var file = fileBuffer.shift(0,1);  // <-- works as expected console.info( file.name + ", " + file.size + ", " + file.type ); // sort files by size fileBuffer.sort(function(a,b) {    return a.size > b.size ? 1 : a.size < b.size ? -1 : 0; });

Tested OK in FF, Chrome, and IE10+

If you are targeting evergreen browsers (Chrome, Firefox, Edge, but also works in Safari 9+) or you can afford a polyfill, you can turn the FileList into an array by using Array.from() like this:

let fileArray = Array.from(fileList);

Then it's easy to handle the array of Files like any other array.