Are you wanting to run group statistics on a subset of groups or do more? If you change the group numbers of the unwanted group to ‘0’, PATN still treats this as a group in the normal fashion and relabels the groups accordingly. We should change this in a later version so that PATN ignores group ‘0’ objects.
One option is to simply save the original dataset as a .ptn file, then highlight the unwanted group members in the Data Table and re-run the analysis.
Hope that helps,