It's a custom add on. Surely it comes off. The serving hole looks like it has been modified too. If I had it, I would remove it. With it on there, you can't serve the ball (by the new rules). You also can't practice aerials which are illegal anyway.
![Wink ;)](https://www.foosball.com/forum/Smileys/ichat/wink.gif)
Just make sure it doesn't affect normal play and don't pay extra for the unnecessary modifications.