2018 Equinox center dash defrost vents vibrate while driving

I've been hearing this noise for a while and mistook it as a loose blend door but today it started and I reached up and grabbed the passenger side defroster vent in the middle of the dash and it stopped.

I want to insert a pad underneath the dashboard to isolate it so it doesn't recur but it appears that the two vents are glued into the dash itself. How do I get the vents out so I can place an isolator underneath the dash?