Removing traces of an email address

Hi all

A user has signed up to our forum using a personal email address, later changing it to a different one. They’ve asked if there are any traces of their personal address kept.

I’m aware there are entries on the email log, but is there anywhere else, for example, a change log? And to further that, how would I go about removing these entries, or removing the link with the individual and anonymising them?

Thanks in advance!