To uninstall xboard just follow these instructions.
sudo apt-get remove xboard
This will remove just the xboard package itself.
sudo apt-get remove --auto-remove xboard
This will remove the xboard package and any other dependant packages which are no longer needed.
If you also want to delete your local/config files for xboard then this will work.
sudo apt-get purge xboard
Or similarly, like this xboard
sudo apt-get purge --auto-remove xboard
|Maintainer||Debian Games Team <firstname.lastname@example.org>|
|Description||X Window System Chess Board for chess programs, for the Internet Chess Server, or for electronic mail correspondence chess. It supports all major forms of chess, such as international chess, xiangqi and shogi. XBoard can also be used by itself as viewer for stored chess games.|