Find the dom0 of the VM on cmucc.org/~kbare/list-xen.cgi
1: On the dom0, run "xen-delete-image $WHATEVER_VM".
2: On the dom0, delete the symlink in /etc/xen/auto to the VM image.
3: Check whether the machine is in monitor.club.cc.cmu.edu and if it is, disable all checks. It will be automatically removed later.
4: Remove its DNS entry.
You should find all the lines matching the pattern below in /afs/club/service/dns/DB.club.cc.cmu.edu and remove them.
XXXXXX.club.cc.cmu.edu:127.237.157.XXX:7200
5: Update the wiki and move the machine's entry into Decommissioned.
6: Remove the entry from netreg.net.cmu.edu
7: Think hard about whether you have forgotten anything important.