untell and its cross-references

untell

untell <nick> ...
 Forgets about all message(s) you've sent with tell to particular
 nick(s).  Use delmsg to delete messages sent *to* you.  There is no
 way to untell individual messages to the same nick.  If your nick is
 secure, you must identify yourself to use untell.

delmsg

delmsg [<nick> ...]
 Forgets about tell messages I've passed on: either all of them, or
 only those from certain nicks.  Necessary if you set tellme pester
 or reliable, and also works with remind, but not with unreliable.
 Use untell to delete messages you've sent, rather than received.

identify

You must identify yourself to change your settings if your nick is
secure, and to use channel management commands.  In ircII on chiark,
just say `/blight-id'.  For other clients, see `help identpass'.
Once you are identified you can then register new nicks, change
settings, etc. - so long as you remain on a channel that I'm on too
(see `help invite').  See also `help register'.

tell

tell <nick> <message ...>
 Leaves a message for someone, which will be delivered according to
 their `set tellme'.  I will tell you about your undelivered tells
 whenever I see you arriving, or when you say `ping'.  See also
 `help untell' and `help delmsg'.