GO SMS PRO is a text messaging app.
Under my CONTACTS, I have created different people "Groups" .
I wish to delete one of my groups.
I do not see a way to delete a specific Group.
So like I said, if you wish to delete a contacts group you should do it using the contacts app. You didn't create it in Go SMS, so why would you think that Go SMS could delete it?
I don't have the Samsung S7 contacts app to test with (it will be a Samsung app, so different from mine), but go into your list of groups in the contacts app and try a long press on the group name and see what options you get, or else try to edit the group and look for a context button (3 dots). It will just depend on where Samsung have put the delete option.