Hey there Lynne Roberts - I've been looking into this and it does look like the inability to delete federated permission groups was addressed in Jive 7.0.3 and newer in bug JIVE-46798. In older versions the "Delete" button is missing, while it has been added in later versions:
The only way I've found to work around this issue in older versions where the "Delete" button isn't present is to use Jive's v3 API system to delete a group through an API call.
This is something you can do to clear out unused federated permission groups through a developer building a custom script to delete these. There is some documentation on this API service here: Jive REST Rest API v3.9 → SecurityGroup entity