The TVTropes Trope Finder is where you can come to ask questions like "Do we have this one?" and "What's the trope about...?" Trying to rediscover a long lost show or other medium but need a little help? Head to Media Finder and try your luck there. Want to propose a new trope? You should be over at You Know, That Thing Where.
If it's still technically in the game's code somewhere, then Dummied Out.
If it was added with the intention of removing it later, like one time special events, Temporary Online Content.
If you mean more through general balancing efforts of a competitive game, like say League of Legends removing a certain item (out of a few dozen options) from the shop while adding another one, it doesn't seem noteworthy to me. That's what patch notes are for.
What Could Have Been could be your one.
A game has something in it, but it's cut out in a later update. What trope is this?