Extjs 4.2.x Grid Reconfigure: Reusing Grid's Columns (remove some)

Hi,

The objective is to Reconfigure a Grid by reusing the existing Grid's column (40) but deleting 5 columns from that (leaving 35 fields).

Here is my code so far (codes with ???? are undone)

Code:

//Reconfigure the Result Grid
var newStore = Ext.getStore('Overall_Information_2_External');
var theGrid = Ext.getCmp('overallInformationPanel');
var columns = theGrid.getView().headerCt.getGridColumns();
// ???? needs to process columns as this returns [object Object], [object Object]........
// ???? delete columns by index, or by key 
var newColumns = // 40 columns - 5 columns
theGrid.reconfigure(newStore, newColumns);