So, trying to start over again. I did this
sudo apt-get remove --purge munin
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED:
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
Need to get 0B of archives.
After unpacking 1020kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 33786 files and directories currently installed.)
Removing munin ...
Purging configuration files for munin ...
The generated web site or accumulated data won't be removed.
dpkg - warning: while removing munin, directory `/etc/munin' not empty so not removed.
dpkg - warning: while removing munin, directory `/var/run/munin' not empty so not removed.
dpkg - warning: while removing munin, directory `/var/www/munin' not empty so not removed.
And it didn't remove everything - according to the warnings. Last time I went and removed all that by hand and I think that's how I got into trouble the first time.
What do I do next to _really_ remove munin so I can reinstall it fresh and have it 'just work' like it did the first time?