Session Kill on Page Refresh OR On Page/Browser refresh session kill in asp.net with c#

Create a Global Variable

bool IsPageRefresh = false;

Write Below Code on Page Load

  #region To Maintain Refresh event
  //Section of code checks if the page postback is due to genuine submit by user 
  //or by pressing "refresh" or F5
  if (!IsPostBack)
  {
       Session.Abandon(); Session.Clear();
       ViewState["ViewStateId"] = System.Guid.NewGuid().ToString();
       Session["SessionId"] = ViewState["ViewStateId"].ToString();
  }
  else
  {
      if (ViewState["ViewStateId"] != null && Session["SessionId"] != null)
        {
          if (ViewState["ViewStateId"].ToString() != Session["SessionId"].ToString())
            {
               IsPageRefresh = true;
            }
        }

        Session["SessionId"] = System.Guid.NewGuid().ToString();
        ViewState["ViewStateId"] = Session["SessionId"].ToString();
    } 
    #endregion 

Check Global variable where you made the condition like on events

    #region To Maintain Refresh event
     if (IsPageRefresh)
        {
          Session.Abandon(); Session.Clear();
        }
    #endregion

    if (Session["MyFlag"] == null) Response.Redirect("invalid.aspx?msg=Session expired. ", true);