Okay, few questions.
1. How do I image the server?
2. How do I delete ZPanel?
Check through your sign-up e-mails, but there is a special area where you can connect in, and wipe/reinstall the machine. They've got like CentOS, Debian, Gentoo, Slackware, and Ubuntu, and I believe some of the CentOS images come pre-configured with Kloxo.
If not, you could certainly choose CentOS 5.8/9 and do it yourself, it's pretty simple, even easier with that guide. By re-imaging the server, you've wiped out any trace of ZPanel, and anything else for that matter.
You could also put in a ticket with the urlhasbeenblocked staff, they're pretty good and helpful with things like that.