balderdash. A person should absolutely be free to live or free to choose to die.
They are free, that's free will, it's stil wrong to do it.
Remember that "morals" are something that you believe. Each person's are a little different, even within the same subculture.
You're confusing a personal code with morality. Your personal code is your best guess about what is right and wrong, cobbled together from your personal experiences.
It's no different from your personal understanding of how physics work vs. actual physics. I don't grasp 1% of relativity, but I still know gravity pulls things down, and that on earth things will accelerate at roughy 9.8 m/s^2. Similarly, I'm not a doctor, but I realize that releasing a dense object over someone's head will result in an impact that may fracture their skull and severely injure them if not kill them. And I have never had a skull fracture, but I can infer that it would be painful or fatal.
Thus, even with limited information, I know it's wrong to drop a bowling ball on someone's head. Different people might come to the same conclusion in different ways, but the fact that they will all come to roughly the same conclusion demonstrates that the underlying truths were always there whether or not some arrogant humans stumbled across them.
I certainly don't find anything immoral in killing oneself. You do. So for you, it would be immoral to kill yourself. For others, not so much. But don't try to pass off the definition of morality that your own ego holds as being some central morality that we all should subscribe to.
Okay, then kill yourself. Not dead yet? That's because you have a life to live, which has an inherent value. It's self-evident, and you've been basing decisions on that inherent value the whole time, not killing yourself obviously, but also trying to better yourself, provide an example to others, etc.