var deleteBttn = Ext.query('td.x-action-col-cell img',grid.getNode(rowIndex))[0];
deleteBttn.src = 'http://etf-prod-projects-1415177589.us-east-1.elb.amazonaws.com/trac/docasu/export/2/trunk/client/extjs/shared/icons/fam/add.gif';
By adding the above code in the handler section fixed it.