Due to noise and smoke from upstairs neighbor (live in apartment building), I want to plug up the vent fan opening in our bathroom. We have other means of venting the steam during showers.

QUESTION: What material would work best? I only want to remove the fan grate and plug the hole in the wall (approx. 12" x 12"), in a manner that I could "undo" if/when we decide to move from the apartment. I was thinking acoustic tile over a piece of plywood. Any suggestions?