To enable the editing feature on some specified columns, set 'editor' property for these columns. Remove 'editor' property will disable the editing functionality.
var col = $('#dg').datagrid('getColumnOption', filename);
col.editor = {
  type:'datebox',
  options:{
    required:true
  }
};
$('#dg').datagrid('beginEdit', index);
Running the code below can't edit the specified column since its 'editor' property is null.
var col = $('#dg').datagrid('getColumnOption', filename);
col.editor = null;
$('#dg').datagrid('beginEdit', index);