Image is used by another process and not able to delete

Question

I'm trying to delete image after deleting record from list in wpf C#. but it always throw exception that file is used by anohter process and not allow me to delete.

 

string appPath = Path.GetDirectoryName(System.AppDomain.CurrentDomain.BaseDirectory) + @"\screenshots\";

string schemename = selectedStockObject.Name.ToString();

objSchemeBLL = new SchemeBLL();

Scheme objTemp = objSchemeBLL.getSchemebyName(schemename);

 

GC.Collect();

Thread.Sleep(20);

File.Delete(objTemp.ImgPath);