If you delete an account, you can choose to archive the account's data. The
users' files will be tarred, gzipped and saved in the oldaccounts
directory in the default home directory.
For example, if you're archiving a login account's data, the user's home
directory (probably /home/username) and the user's e-mail inbox
(probably /var/spool/mail/username) will be tarred, gzipped and saved
in the /home/oldaccounts directory. These paths will vary according to
the default home directory on your system.
If you decide at a later time that you need data from the user's files, you can use tar and gzip to recover the files. If you need to conserve storage space, you may choose to move the tarred and gzipped file to a storage site off your system.