If you're talking about removing the pre-fixed column names from the values after grouping, you can subscribe to the GroupSummaryEvaluate
event, and then override the default formatting.
For example, if your column names are "Rotulo" and "Termino", as it appears in your example:
void radGridView_GroupSummaryEvaluate(object sender, Telerik.WinControls.UI.GroupSummaryEvaluationEventArgs e)
{
if ((e.SummaryItem.Name == "Rotulo") || (e.SummaryItem.Name == "Termino"))
{
e.FormatString = e.Value.ToString();
}
}