Stop orCancel aWorkflow programaically

SPSecurity.RunWithElevatedPrivileges(delegate() { 

                using (SPSite site = new SPSite(SPContext.Current.Site.ID)) 

                { 

                    using (SPWeb web = site.OpenWeb()) 

                    {  

                        SPWorkflowManager manager = site.WorkflowManager; 

                        //SPList currentList = web.Lists["Implementation Details"]; 

                        //int id = Convert.ToInt32(Request.Params["ID"]); 

                        SPListItem lstimpitem = GetListDetails("Implementation Details", Request.Params["ID"].ToString()); //currentList.GetItemById(Convert.ToInt32(Request.Params["ID"])); 

                    

                        //SPListItem item = web.Lists[properties.ListTitle].GetItemById(properties.ListItemId);  

                         

                        foreach (SPWorkflow workflow in manager.GetItemActiveWorkflows(lstimpitem)) 

                        {  

                            foreach (SPWorkflowTask t in workflow.Tasks)  

                            { 

                                t.Web.AllowUnsafeUpdates = true; 

                                t["Status"] = "Canceled"; 

                                 

                                t.Update(); 

                                SPWorkflowManager.CancelWorkflow(workflow); 

                                t.Web.AllowUnsafeUpdates =false; 

                                string message = "Workflow is cancelled successfully"; //  + mailUsers.TrimEnd(',') + "\\\""; 

                                Context.Response.Write("<script type='text/javascript'>alert('" + message + "');window.frameElement.commitPopup();</script>"); 

                                Context.Response.Flush(); 

                                Context.Response.End(); 

                                 

                            } 

                           

                             

                        }  

                    }  

                }  

            });