To uninstall context-doc-nonfree just follow these instructions.
/parrot/jollyroger/non-free///install/index.html ConTeXt documentation that is not DFSG free documenting many features of ConTeXt and friends. These documents are only available as pdf documents. Parrot 3.7 non-free/doc 2012.06.27-4
sudo apt-get remove context-doc-nonfree
Which will remove just the context-doc-nonfree package itself.
sudo apt-get remove --auto-remove context-doc-nonfree
This will remove the context-doc-nonfree package and any other dependant packages which are no longer needed.
If you also want to delete your local/config files for context-doc-nonfree then this will work.
sudo apt-get purge context-doc-nonfree
Or similarly, like this context-doc-nonfree
sudo apt-get purge --auto-remove context-doc-nonfree
|Maintainer||Debian TeX maintainers
|Description||ConTeXt documentation that is not DFSG free documenting many features of ConTeXt and friends. These documents are only available as pdf documents.|