deluser
AccountsPackage: adduserHandle with care
Removes an account. Without --remove-home its files stay, now owned by a UID with no name; with it, they are gone. A service still running as that account is not stopped for you.
A mistake with this command can destroy data or lock you out
deluser --remove-homedeletes the home directory and the mailbox without confirmation. First check what the account owns elsewhere (find / -user <name>): those files stay behind, orphaned.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
deluser --remove-home- Also deletes the home directory and mail spool. Without it the files stay, owned by a number with no name.