How do I remove myself from academic mailing lists?
Sadly, that sounds like spam, and you should treat it however you'd treat spam.

I'm not sure you should assume good faith on the part of the people sending you those e-mails.  I'm an active academic with an e-mail address accessible on my university website, and I receive:


Legitimate conference announcements over e-mail lists used by people in the area, which I could unsubscribe from if I wished.
Announcements from people who actually know me.
Unsolicited announcements from scam journals and conferences.


I receive several of the last category every week (and more, unsurprisingly, than any other category).  I do not get legitimate mass e-mails that are not in the first two categories.  It's possible that in other fields there are some legitimate announcements sent the way you describe, but I'd guess very few.

In other words: spam is spam, and you should feel no compunctions about treating it that way.