User blog comment:Tholanar/What would you do if you were the Emperor of Tamriel?/@comment-5450493-20130112194148/@comment-5709731-20130113170515

As far as I know, the closest you get to killing any Et'Ada/God, is by removing it's heart. The heart and the god's plane are, as far as I know, as one. Lorkhan's Heart was shot down unto Nirn, and in doing so, fused his Plane of Oblivion, Dawn's Beauty, into the plane of Nirn. Thus, I assume a God's plane(t) to be their body, and their hearts being the core of the plane. Lorkhan is dead by all means, and all that is left is his spirit, just like when a mortal dies. Said spirit has been tasked with overseeing the souls of his faithful, the nords. In the plane of Stasis, no less. What a horrible fate for a Daedra. :D

Anyway, to kill a god, remove it's heart. It will render the god as powerless as a ghost (Even though they can be quite a pain to defeat sometimes).

Conclusion: To kill the daedra, you must face them in combat, defeat them, and remove their heart. You will then hold every ounce of their power, and tecnically hold an entire plane of Oblivion/Aetherius in your hands. But, reaching the princes, even in their home dimension, is often quite hard. And defeating them? Even the Nine Divines, who are the weakest gods currently known, dwarfs any mortals power. The Daedra are at their full power, like Magnus, because they did not participate in the worlds creation. Any daedra would be able to crush you like a bug if he/she wanted.