For source code installations, here are the install/uninstall commands...
Installing asciidoc for all users
Create configure using autoconf(1); use configure to create the Makefile; run make(1); build the man pages; install:
$ autoconf
$ ./configure
$ make
$ sudo make install
To uninstall:
$ sudo make uninstall
Source: http://asciidoc.org/INSTALL.html
Update #1
For binary installations...
dpkg -l *ascii* | grep ii
un asciidoc <none> <none> (no description available)
ii asciidoc-base 8.6.10-3 all Minimal version of asciidoc not suitable for pdf
ii asciidoc-common 8.6.10-3 all Basic data and configuration files for asciidoc un asciidoc-doc <none> <none> (no description available)
To completely uninstall asciidoc, you'll need to run all of these commands...
sudo apt-get purge asciidoc # already done
sudo apt-get purge asciidoc-base
sudo apt-get purge asciidoc-common