The metal ring is part of the EMI protection so the signals don’t cross pollenate noise to the neighboring lines. The concept is similar to how a [https://en.wikipedia.org/wiki/Faraday_cage|Faraday Cage] works.
I would leave it be as the tarnish on it won’t affect it, but that’s assuming the contacts are not tarnished or damaged. Besides, removing it will likely destroy the connector interface.