Modify Users

Hi –
I’m sure this has been asked before, but I didn’t see it by searching “change user” or “modify user” or “modifying users”.
Is it possible to modify an existing WP user? I have one who cannot remember his password, and the “email password” won’t work because his email address is invalid also. I don’t want to delete and re-add the user, because I’ll lose his posts. But I don’t see any way of editing or modifying the user’s password, email address, etc – only changing this level of permissions?
Thanks in advance,
Fred McKinnon
http://www.fredmckinnon.com/myblog/index.php