One must distinguish between the right and the exercise of the right. If I own a house, then I sure have a right to use it. But for just reasons the law can prevent me from exercising that right, for example, by putting me in jail. Of course, I still have the right to use the house while I am in jail, but by keeping me in jail the law has effectively deprived me of the ability to* exercise* that right.
The same distinction applies to the right to life. No one can really take away your right to life because it is a natural and inalienable human right. It belongs to you just because you are human. You can’t lose it, or forfeit it, as long as you are human, because it is not an accident, but a property of your human nature. However, you can, for just reasons, be deprived of the ability to exercise that right. Indeed, this important distinction between your right to life and your ability to exercise that right, is the only reason why killing an unjust aggressor is justified in the case of self-defense. For you are not depriving an unjust aggressor of his right to life, but simply incapacitating him from the exercise of that right.
I understand where some people have a problem with this distinction between the right and the exercise of the right. But it is a valid distinction. As a citizen, for example, you might have a right to vote. During an election, however, you might abstain from exercising that right without losing your right. The exercise of the right to life, however, is somewhat problematic in the sense that you can only deprive a person of the ability to exercise that right by killing the person. And, of course, when you kill the person, then that person becomes a corpse and ceases to be human - and, not being human, the corpse possesses no more rights. So, when a person dies, he does not merely lose the ability to exercise his right to live, but also loses his right to live. But from your standpoint, you did not during self-defense rob him of his right to live, but simply stopped him from exercising that right.