To uninstall debdelta-doc just follow these instructions.
/debian/stretch/main///install/index.html diff and patch utilities which work with Debian packages Debian 9.0 doc 0.59
sudo apt-get remove debdelta-doc
Which will remove just the debdelta-doc package itself.
sudo apt-get remove --auto-remove debdelta-doc
This will remove the debdelta-doc package and any other dependant packages which are no longer needed.
If you also want to delete your local/config files for debdelta-doc then this will work.
sudo apt-get purge debdelta-doc
Or similarly, like this debdelta-doc
sudo apt-get purge --auto-remove debdelta-doc
|Description||diff and patch utilities which work with Debian packages|