File Upload - Exception In Deleting Image Uploaded To The Server?

In asp.net, we have uploaded a .jpeg file and saved this as bitmap image using following code

HttpPostedFile uploadFile;
System.IO.Stream stream = uploadFile.InputStream;
using (System.Drawing.Image imgSource = System.Drawing.Bitmap.FromStream(stream))
{
System.Drawing.Image.GetThumbnailImageAbort myCallback = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
using (System.Drawing.Image imgThumbnail = imgSource.GetThumbnailImage(imgSource.Width, imgSource.Height, myCallback, IntPtr.Zero))
{
imgThumbnail.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
imgThumbnail.Dispose();
}
imgSource.Dispose();
}
stream.Close();
stream.Flush();
stream.Dispose();

After upload, if we perfrom delete operation it throws error. We are following code to do so;

if (File.Exists(filePath))
{
File.Delete(filePath);
}

The exception says:The process cannot access the file 'abc.jpg' because it is being used by another process.