code: function() {
      var elBdThead = this._elBdThead;
      if(elBdThead) {
          var elTable = elBdThead.parentNode;
          Ev.purgeElement(elBdThead, true);
          elTable.removeChild(elBdThead);
          this._elBdThead = null;
  
          this._destroyColumnHelpers();
      }
  }
docs: Destroy's the DataTable body THEAD element, if available.
  
  @method _destroyBdTheadEl
  @private