Preload/Delete images from Mini Ajax File Upload Form

I am using the mini ajax upload form available HERE I have slightly modified the code in the script.js to show the image preview. Here is the new script.js code:

$(function(){

var ul = $('#upload ul');

$('#drop a').click(function(){
    // Simulate a click on the file input button
    // to show the file browser dialog
    $(this).parent().find('input').click();
});
var n = 0;
// Initialize the jQuery File Upload plugin
$('#upload').fileupload({

    // This element will accept file drag/drop uploading
    dropZone: $('#drop'),

    // This function is called when a file is added to the queue;
    // either via the browse button, or via drag/drop:
    add: function (e, data) {
                    if(data.files[0]['type'] != 'image/png' && data.files[0]['type'] != 'image/jpg' && data.files[0]['type'] != 'image/jpeg'){ 
                        alert("Only .png, .jpg, and .jpeg allowed."); 
                        return; 
                    }

        var tpl = $('<li class="working"><input type="text" value="0" data-width="48" data-height="48"'+
            ' data-fgColor="#0788a5" data-readOnly="1" data-bgColor="#3e4043" /><p></p><span></span></li>');

                    //previewImage(data);
                    var reader = new FileReader();

                    reader.readAsDataURL(data.files[0]);          
                    reader.onload = function (ev) {
                            console.log("reader.onload e.target.result: "+ev.target.result);
                            data.cntxt.after("<img src='"+ev.target.result+"' width=240 style='display: block; margin-left: auto; margin-right: auto;' height=auto class='imgUploading'>");

                            data.cntxt.next("img").after(photoTitleVar);
                            data.cntxt.next("img").next("legend").next("label").after(photoDescriptionVar);
                            //alert(ev.target.result);
                            //alert("hello");
                    }
        // Append the file name and file size
        tpl.find('p').text(data.files[0].name).append('<i>' + formatFileSize(data.files[0].size) + '</i>');

        // Add the HTML to the UL element
        data.cntxt = tpl.appendTo(ul);

        // Initialize the knob plugin
        tpl.find('input').knob();

        // Listen for clicks on the cancel icon
        tpl.find('span').click(function(){

            if(tpl.hasClass('working')){
                jqXHR.abort();

            }

            tpl.fadeOut(function(){
                tpl.remove();

            });
            tpl.next("img").fadeOut(function(){
                tpl.next("img").remove();
            });

        });

        // Automatically upload the file once it is added to the queue
        var jqXHR = data.submit();
    },

    progress: function(e, data){
        // Calculate the completion percentage of the upload
        var progress = parseInt(data.loaded / data.total * 100, 10);

        // Update the hidden input field and trigger a change
        // so that the jQuery knob plugin knows to update the dial
        data.cntxt.find('input').val(progress).change();

        if(progress == 100){
            data.cntxt.removeClass('working');
                            //change img css opacity once loaded -Should I change the style directly?
                            data.cntxt.next("img").removeClass("imgUploading");
                            data.cntxt.next("img").addClass("imgUploaded");
                            $("#uploadInfo :submit").removeAttr("disabled");                                
        }
    },

    fail:function(e, data){
        // Something has gone wrong!
        data.cntxt.addClass('error');
    }

});


// Prevent the default action when a file is dropped on the window
$(document).on('drop dragover', function (e) {
    e.preventDefault();
});

// Helper function that formats the file sizes
function formatFileSize(bytes) {
    if (typeof bytes !== 'number') {
        return '';
    }

    if (bytes >= 1000000000) {
        return (bytes / 1000000000).toFixed(2) + ' GB';
    }

    if (bytes >= 1000000) {
        return (bytes / 1000000).toFixed(2) + ' MB';
    }

    return (bytes / 1000).toFixed(2) + ' KB';
}





});//end function i.e. document.ready

Now I have 2 questions based off of this form because i want to allow users to be able to delete images and also delete the images from the server, and pre fill the form with images if they want to edit which images they have.

How do I call a php script when the delete function is initiated?

And

How do I pre fill the form with images?