I'm not sure that it is possible to make the fear of death completely go away. It is ingrained in us on the level of instincts, we want to be alive with our body intact and not in pain, and I don't think you can deliberately make the fear of pain, death or injury completely disappear. I watched people around me facing the reality of the war - and most people were constantly terrified at first, but now they are shivering in fear all the time. It's not because anyone got comfortable with the idea of getting their limbs torn off in an explosion or having the walls of their own home collapse on top of them while they're sleeping. It's just because when days of fear turned to weeks and then weeks turned to months, you eventually have no choice but to distract yourself from constantly thinking about your fear, because reality ensues and you have to continue dealing with the mundane. You hear that the crazy megalomaniac prepared the nukes to the attack and you're in an existential crisis, crying, drinking, trying to see your loved ones - but then you sit it out for one day, two days, three days and nukes still ain't coming and while the chance of you dying hadn't gotten any smaller, you still aren't dead and you kind of forced to get a hold of yourself and start doing normal things, such as going to work and doing chores. And as you begin to do it, you put the fear into the back of your mind and the more you stay busy with the mundane - the more it stays put somewhere in the back drawer of your consciousness.
I have my own approach to dealing with fears whether rational or irrational. At first, I sit down and try to make a plan. Can anything be done to prevent the things I fear from happening? In your case, not really, regardless of whether you're suicidal or not, becoming immortal is not possible for anyone, so facing death is inevitable at some point. So if I cannot prevent the thing I fear, I think - can I do anything to prepare for it and make it not as horrible for myself? If something comes to your mind, take a sheet of paper and write it down, step by step, in as much detail as possible. If you have people you trust enough to ask them for advice and you believe they can offer a different perspective - ask them and write down their advice too, if it doesn't make you uncomfortable. If you give it a really good think and you can't think of anything that is also okay. Once that is done, if you wrote a plan, you put the sheet of paper somewhere where you can easily access it, but where it isn't in your face all the time. And then you just try not to think about your fear anymore, by keeping busy as much as possible. Every time the fear comes up in your head, you tell yourself "I already thought about this thoroughly" and then either go over your plan of how you're going to prepare for the situation and maybe do some of the stuff you wrote down, or if you didn't come up with anything - you remind yourself "I gave it a good thought, there is nothing I can do about this thing so there is no point in thinking about it again" - and then you distract, distract, distract until the fear goes away. Works quite well for me, it doesn't make the fear disappear completely, but it makes me able to have it and still function like a normal human being and not allow it to control my life, even if that is a "big fear", like being shot in the war.
