You can hide a range of columns using "ColHiddenEntries". Here is the code that could be used to perform the operation.
GridColHidden[] hiddenCols = new GridColHidden[ 3];
for (int i = 0; i < 3; i++)
{
hiddenCols[i] = new GridColHidden(i + 1);
}
this.gridGroupingControl1.TableControl.Model.ColHiddenEntries.AddRange(hiddenCols);
I hope this would simplify your task of removing columns.