If you are certain they are dead, remove them from your tank and toss them in the garbage...
There is really nothing "special" that needs to be done. But make sure they are really dead first because sometimes the tissue you can see is damaged and needs to be removed, but there may still be some viable pieces which were not obliterated.
I have had that happen before when the glass broke on the heater several years ago, and I used nail scissors to cut off all the tissue which was obviously dead, and then gave each one a coral dip and replaced it back into the tank to see if anything could be salvaged. Over the next few weeks some actually started budding from within the skeleton and were growing back. Others remained barren, and those were the ones I knew were truley destroyed, so I removed their skeletons and tossed them.
It sucks, but sometimes they can surprise you, so make sure they are really dead and gone before tossing them out.
And be more careful with the heater. Make sure it's not free floating and banging around in your sump. If you cannot secure it completely, purchase a guard to buffer it from future mishaps.