ASP.Net Error: Access to the path is denied

I made the following changes  to the Application manifest file:

<requestedExecutionLevel level="asInvoker" uiAccess="false" />
<requestedExecutionLevel level="requireAdministrator" uiAccess="false" />
<requestedExecutionLevel level="highestAvailable" uiAccess="false" />

This gives me the following error: 

How to allow the Application to allow client to access a folder on the server?

Codebehind: 

$("#ContentPlaceHolder1_btnNext").click(function () {
    var canvas = paper.project.activeLayer.view.element;
    var img = $(canvas).parent().find('img')[0];
        var mergeCanvas = $('<canvas>')
        .attr({
            width: $(img).width(),
            height: $(img).height()
        });
 
    var mergedContext = mergeCanvas[0].getContext('2d');
    mergedContext.clearRect(0, 0, $(img).width(), $(img).height());
    mergedContext.drawImage(img, 0, 0);
    mergedContext.drawImage(canvas, 0, 0);
          
    var image = document.getElementById("canvas").toDataURL("image/png");
    image = image.replace('data:image/png;base64,', '');
    $.ajax({
        type: 'POST',
        url: 'home.aspx/MoveImages',
        data: '{ "imageData" : "' + image + '" }',
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        success: function (msg) {
        }
    });
});

[System.Web.Services.WebMethod(EnableSession = true)]
public static void MoveImages(string imageData)
{
        string xyz = HttpContext.Current.Session["HiddenField1"] as string;
        string fileName = xyz; 
        string pathstring = @"D:\............";               
        string destFile = System.IO.Path.Combine(pathstring,..);
        string destFile1 = System.IO.Path.Combine(destFile, fileName); 
                 
        if (File.Exists(destFile1))
        {
            File.Delete(destFile1);
        }
        else
        {
            using (FileStream fs = new FileStream(destFile, FileMode.Create))
            {
                using (BinaryWriter bw = new BinaryWriter(fs))
                {
                    byte[] data = Convert.FromBase64String(imageData);
                    bw.Write(data);
                    bw.Close(); 
                }
            }
        } 
    }
}