You can do this dynamically in DrawCellDisplayText. This way you do not modify the actual datatable values, but instead just change what the grid displays.
private void gridDataBoundGrid1_DrawCellDisplayText(object sender, GridDrawCellDisplayTextEventArgs e)
{
int col = e.Style.CellIdentity.ColIndex;
if(this.gridDataBoundGrid1.Binder.NameToColIndex("Col2") == col)
{
if(e.DisplayText == "0")
{
e.DisplayText = "";
e.Cancel = true;
}
}
}