To uninstall debian-keyring just follow these instructions.
/debian/stretch/main///install/index.html GnuPG keys of Debian Developers and Maintainers Debian 9.0 misc 2017.05.28
sudo apt-get remove debian-keyring
Which will remove just the debian-keyring package itself.
sudo apt-get remove --auto-remove debian-keyring
This will remove the debian-keyring package and any other dependant packages which are no longer needed.
If you also want to delete your local/config files for debian-keyring then this will work.
sudo apt-get purge debian-keyring
Or similarly, like this debian-keyring
sudo apt-get purge --auto-remove debian-keyring
|Maintainer||Debian Keyring Maintainers
|Description||GnuPG keys of Debian Developers and Maintainers|