Archives are located at /x1/archives, /x1/private, /x1/restricted. These hold the emails archived by the host, which started operating in Aug 2017.
Earlier mails were archived by minotaur; copies of these files are held under:
/x1/minotaur/apmail/private-arch/, /x1/minotaur/apmail/public-arch/, /x1/minotaur/apmail/restricted-arch
Note that most lists were archived by both minotaur and mbox-vm until minotaur was decommissioned.
Month end was handled differently by minotaur and mbox-vm, so emails received near the end of a month may appear in different months in the mbox-vm and minotaur archives.
Locate the archive file(s) you want to edit, for example '/homex1/apmailarchives/public-arch/httpd.apache.org/dev/202008.mbox'
Back it up so you have a copy to retreat to in case something goes wrong, then open it in Vim or your favourite editor, find the email via a quick search, then carefully delete it,
starting with 'From ' and ending just before the next 'From '. Save the file.e
Warning: in earlier mails archived by minotaur, a 'From ' line which appeared in the body of an email was not correctly escaped, so can be matched by mistake.
Archives are located at /x1/mail-archives.apache.org/mod_mbox/