clsDB.Delete_byID(IDProject_on_Server);

public static void Delete_byID(long id)

{

    //----------< Get_RefNr_OnServer_toDelete()>------------

    var db = new dbAppData_Context();

    tbl_Scans recordset = db.tbl_Scans.FirstOrDefault(s => s.IDScan == id);

    if (recordset != null)

    {

        db.tbl_Scans.Remove(recordset);

        db.SaveChanges();

    }        

    //----------</ Get_RefNr_OnServer_toDelete()>------------

}