Working with a smart app that creates child devices, It would appear that if the child device(s) are moved into a group, they are not deleted when the app is uninstalled.
The are deleted properly as long as they aren’t assigned to a group after being created.
After the app is removed, the devices that were in the groups cannot be deleted after the fact.
I have that exact problem now. A “ghost” Hue Bridge remains in a group - I’m unable to delete it, and the Hue (Connect) Service Manager is now unable to find my Hue Bridge.
After a little bit of back-and-forth with Customer Service, I am now completely resetting the ST hub and starting from scratch.