The obvious solution is to ban commenting altogether. On balance, it's just a bad idea. And the commenters. Ban everything, delete the site, degauss the drives and throw the server out of the window. Then throw a bigger, bulkier server out of the same window so it lands on the first server. Then break both servers down until their components are indistinguishable from one another, and mix them together. Then separate them into a number of small piles and hide each pile inside of a complex puzzle box - a different puzzle for each - in different sacred locations around the world, protected by whatever spells or enchantments are culturally appropriate. Then kill anyone who knows the location of the puzzle boxes, dissolve their bodies in lye, mix the lye into concrete blocks and dispose of the blocks in international waters, following a random dispersal path. Then blow up the boat with an orbital laser. Methods for the procurement and operation of an orbital laser are left as an exercise for the reader.
It's the only way to be sure.