erc-ignore-reply-list

erc-ignore-reply-list is a variable defined in `erc.el'.
Its value is

nil

Documentation:
List of regexps matching user identifiers to ignore completely.

This differs from `erc-ignore-list' in that it also ignores any
messages directed at the user.

A user identifier has the form "nick!login@host".

If an identifier matches, or a message is addressed to a nick
whose identifier matches, the message will not be processed.

CAVEAT: ERC doesn't know about the user and host of anyone who
was already in the channel when you joined, but never said
anything, so it won't be able to match the user and host of those
people. You can update the ERC internal info using /WHO *.

You can customize this variable.