Recapture Image error

Question

By Recapture image occur error "The process cannot access the file because its used by another process."

my code is below  i try to delete existing file but not successed. 

[WebMethod()]
       public static bool SaveCapturedImage(string data)
       {
           string fileName = DateTime.Now.ToString("dd-MM-yy hh-mm");
           //string fileName2 = DateTime.Now.ToString("dd-MM-yy hh-mm");
           //Convert Base64 Encoded string to Byte Array.
           //if (File.Exists(fileName2))
           //{
           //    File.Delete(fileName2);
           //}
           //else
           //{
               byte[] imageBytes = Convert.FromBase64String(data.Split(',')[1]);
               //Save the Byte Array as Image File.
               string filePath = HttpContext.Current.Server.MapPath(string.Format("~/CapturedImage/{0}.jpg", fileName));
               File.WriteAllBytes(filePath, imageBytes);
               return true;
           //}