That island was once part of Numenor, which supposedly sunk entirely! Canon violation! Mevans needs to make an invisible Numenor-shaped biome around Meneltarma so that no islands spawn!
Yes, it would also be invisible. Everything would look the same! (And don't remove Meneltarma, just keep the invisible biome around it!) You wouldn't see it on the map, on the map compass bar, or anything else. The only way you could know you were in it would be pressing F3, and even then, Numenor is very large! Finding Meneltarma would be difficult.