How to Unsubscribe an email address?

[Alex Avery <aavery@rica.net>]

Both my father and I are on the roadster email list, but the volume of
messages is driving my father crazy (he checks email infrequently, so when
he does check, 600 messages are from the roadster list!).

Since I'm the one actively monitoring the roadster info, how do we get his
email address removed from the list?

If it is possible to do this immediately, his email address is: davery@rica.net

Thanks
Alex