Necron's probably have the most capacity to simply remove planets from existence. Chaos has from time to time been known to rip planets into the warp if that counts. Orks have been known to teleport moon sized objects.
Abaddon's planet killer, any ship with Stage 2 Cyclonic Torpedoes, Some Ork Space Hulks if they build that Super Shokk Attack Gun one Mek did but that was more a case of mutual annihilation when the planet was teleported into the space hulk carrying it and both were destroyed. The Necron World Engine is probably capable of such a feat. A pair of Blackstone fortress could easily crack a planet, three were able to destroy a Star. A sufficiently potent C'tan or Greater Daemon could pull it off. The Tyranids may be able to literally tear one apart should they be pressed to the matter, they can take a noticeable chunk out of a planet but thats more of a "Why would they?" Ork Attack Moonz definitely could, since they could literally turn a star into a Black Hole. Thats honestly something I'd expect from Necrons, not Orks but stuff happens.
The Phalanx could perhaps accomplish this but it has not shown such a capacity.
