I'm not 100% sure how the emitter object type works, but I know that the particle it emits isn't actually part of the emitter object. I think it works in a way similar to tires, they're not an actual object type but they still exist and do things. Since the emitter isn't part of the object that emits it, there wouldn't be a way to remove it instantly, but there are probably workarounds by modifying the emitter itself.