To rid or cleanse one's self of something negative, resulting from utterly stupid and incompetent decisions in the past.
This term originates from the Detroit Lions' incompetent and udderly stupid former CEO and General Manager, Matt Millen.
1. "The upcoming draft and free agency will help the Detroit Lions to de-millenize the roster."
2. "I can't believe I stepped in that pile of dog crap while hopping the fence. Now I need to de-Millenize my Rockports."