This is fairly uncommon, but occasionally we've botched account creation, or someone asks us to get rid of an account. Here's how to clean things up.
Log in as administrator
Remove the afs mount point. Note the dot before club.
fs rmmount /afs/.club.cc.cmu.edu/usr/somebody
Remove the afs volumes. This should remove the backup volumes too.
vos remove -id mail.somebody vos remove -id user.somebody
Remove the pts entries
pts delete somebody pts delete somebody.mail
Remove the user from /afs/club.cc.cmu.edu/service/etc/passwd.user
Remove the file from /afs/club.cc.cmu.edu/service/mail/mailtabs/
Delete the kerberos principals. Make sure to delete both somebody and somebody/mail.