So out of the 8 replies so far
@Reefahholic has the most sure fire way to rid said rock, or rocks, of vermited snails. To supplement what they said using muriatic acid one needs to be safe and it needs to be done out doors. It will not only kill the entire rock and its respected bio diversity it will remove anywhere from 10 to 25% of the rocks surface area. So in short these rocks will be starting from scratch - all over again.
But wait, there is more. These rocks have the snails. It goes further than that. Your plumbing more than likely also has the snails. So does the sump or side of pumps and other equipment or even darker areas of the display like a mini crypitc zone. What I'm saying is that you know you have them because they are visible but I'm also saying there are more. So remove the rock, acid trip it, and you will more than likely have them again in a few months. The root of the problem isn't solved.
I'm not so sure Bumblebee snails really do the trick either. I know there is a lot on this forum with anecdotal evidence but when one widens the search across other articles and forums the answer is usually vague without proof of said snail eating them. It is true they are predators so other snails and clams are at risk should you go down this path. I've also read wrasses and some crabs like mitrax or emerald but again not seen any proof outside of wrasses snipping the cloud of food from manual removal. So to circle back what to do:
1. Dental device, pick, and jab inside the tube reaching down inside to crush snail
2. Bone cutters at base of rock
3. Super glue - glove up, dab on finger, place finder on worm
4. Forceps - clamp at base and break off
5. Remove rock or rocks or equipment with pests to clean
6. Citrix acid soaks on pumps - might as well clean equipment while purging snails
7. Reduce feeding if you can (stop reef roids, other coral foods) to the bare minimum while doing any of these
8 Lastly - Muriatic acid bath - last resort in my opinion
If you look at that list you see that I do not promote any "known - factual" predator of vermited snails. Everything is manual removal over time. That is all I got. All the best and remember nothing happens fast in this hobby. Especially with these since there is not a known predator for home aquaria.