On some linux distro's you can also use the "info [command]"
as in:
info usermod
You need to take care when changing ownerships as this user may have had scripts, crons etc that was run by himself and they may complain at a file ownership change.
Otherwise, I guess that you could do something similar to this:
1) usermod -e <todays date> <user> # to expire that users login.
2) check in /var/spool/cron # and check for any cronfile belonging to that user and check it for clues to what he/she may have croned.
3) check /etc/groups #to confirm that no other users are members of his/her group, else they may start complaining.
4) cd /path/to/home/of/that-user and do: chown -R newuser:newusersGID /path/to/home/of/that-user # this will pass owneship of all files for that user to newuser
That should do it ?
Good Luck
Laurie.