Let's say you don't want to run the Mailman mailing list manager. Since this is a default option in cPanel, there are several steps to completely disable it.
Note: new VPS's do not have Mailman enabled by default.
Disabling Mailman for cPanel Users
Log in to WHM
Navigate to Server Configuration and then Tweak Settings
Scroll down to Mail and uncheck the box for Mailman
Scroll to the bottom and click Save
Removing the Mailman Alias in Apache
Using SSH to connect to your server and login as root
Edit 'httpd.conf' (do not use the Virtuozzo file editor to do this) using vi or nano
Scroll down to these lines:
Alias /mailman/archives/ /usr/local/cpanel/3rdparty/mailman/archives/public/
ScriptAlias /mailman/ /usr/local/cpanel/3rdparty/mailman/cgi-bin/
Alias /pipermail/ /usr/local/cpanel/3rdparty/mailman/archives/public/
#Alias /mailman/archives/ /usr/local/cpanel/3rdparty/mailman/archives/public/
#ScriptAlias /mailman/ /usr/local/cpanel/3rdparty/mailman/cgi-bin/
#Alias /pipermail/ /usr/local/cpanel/3rdparty/mailman/archives/public/
This disables the mailman aliases without removing the entry (you may want it later).
Save the file and restart Apache:
service httpd restart
Removing the cron Entries
While logged in via SSH as root, enter this command:
crontab -d -i -u mailman
This will delete the mailman's nightly cron tasks. Alternately (recommended), you can edit mailman's crontab:
crontab -e -u mailman
Comment out each line by placing a # in front of all the entries. Any line that already starts with a # is a comment.