You can try various techniques to discover where your config files are and then remove them. Some will require starting again from a clean installation of the OS.
- run find over the whole system, looking either for character patterns such as '*tvh*' or for the date you installed TVH or subsequently modified it
- look at the package spec and install records to see if you can find the locations it installs stuff to (e.g. dpkg-deb -c)
- install the system on btrfs or similar filesystem with rollback capabilities, then install TVH
If you want answers about debian or raspbian (why are you using something as old as stretch, BTW?) and their utilities then one of their forums might be a better place to get help.