I would take him out but if you can wash him out of the shell put in back in the tank for your hermits. You just don't want him to rot in the tank and cause ammonia.
deffinately take it out you can put it in a bucket or something till the shell is clear of the snail and it will smell horrid but then after its all cleaned out you can readd it to the tank. the small ones I dont worry about to much the large ones can reak havoke in a tank.
Mike
Depends on the size of your tank, i.e death = nitrates and amm spike. but usually hermits will eat it, an eventually take the shell, i never worry about the ones in my 75. unless they are they BIG ones
If you have a dead Snail that isn't loaded with Bristleworms then you have a Bristleworm shortage.
Take it out if it's not being immediately eaten. A dead Snail can produce an unbelievable amount of ammonia.
If you want to keep the shell just soak it in chlorine for a couple of days.