Don't detach yourself emotionally from the character. Rather, experience the character's death as a major part of their arc.

This is not a real person who is gone once dead; this is a fictional character, and their entire arc is what makes them who they are. Make the specifics of the death contribute towards making the character even greater, and love the character for their entire contribution to your story, including through her death.

You don't detach yourself from the character. On the contrary - you let yourself feel the pain of her death, experience the loss, and you pour all of that onto the page.

When a character dies, it should matter. It should be a punch in the gut for your audience. That can only be achieved if you care about the character. If you don't care, if you've detached yourself, how do you expect the audience to care?

When I write a character's death scene, I try to evoke with the words on the page the same kind of pain I feel at the death of this character I've grown attached to. Then I spend a couple of hours in a zombie state. Then I let other characters grieve, in ways that make sense for them. It's not about me processing my grief - they've lost someone they knew, it should affect them, right? Then, the world move on, I'm writing the next in-story thing.

How to kill a character you are attached to?

ANSWER: Write a few alternate versions of the scene--in one the character dies, in others the character does not die (coma, loss of limbs, etc). Then get on with the story. After you've written more story, with the anaesthetic of knowing you have versions of "that scene" in which the character does not die, you'll reach a point where it becomes easier to pop in the version of the scene in which they do die.

That's how I detach from the characters I must kill. I give myself the stage of grief of denial and numbness, and eventually reach acceptance of the death.

I think this may be a matter of opinion; different psychologies will answer differently.

Personally, my characters feel real to me; but I remind myself of a few things. I go back over what I wrote for her, reminding myself that I invented her, all she really consists of is these words on paper. It is like sketching a person, then burning the sketch. In reality, I kill ALL the characters, sooner or later, when I stop writing about them. They will have their last words, even if I write a series.

What I would like to do for her is give her a meaningful death; I am not just killing her to get her out of the way. Her death will motivate the characters that love her, even if on the surface it looks like a pointless death, it will mean something in how the future of her friends turn out.

You have already said she is kind and caring -- Is she brave enough to knowingly sacrifice herself for her friends? If somebody must die, does she love them enough to make it herself? I think, for the other characters, realizing somebody loved you that much is a powerful emotion that can motivate them to risks and sacrifice they would not have made without her "going first".

Personally I don't kill "good side" characters with stray bullets or other such random events or accidents; if they die, they die fighting. I pay a lot of attention (and often rewrites) to deaths so they will be meaningful and impact the story. And even if the death is meaningless, it can still have an impact upon the characters left behind to grieve and perhaps avenge her. if it doesn't -- You probably did not need this character in the first place.

Second, if I have become attached, that is a good thing. It means you didn't write a cardboard character to kill and forget, just to make a point. Hopefully the reader is also attached, so her death will be meaningful to them.

I don't recommend it, but you can take a Hollywood/American morality play approach. Put something in her current or past behavior that is ever-so-slightly corrupted, or slightly off center, or even the tiniest bit not pure-as-the-gently-driven-snow-virginal. When she dies, rather than address the actual situation or the injustice or the randomness-of-fate inherent in human life, readers will think that she had it coming because she deserved it for the small bit of humanity you exposed.

You will hate yourself. All the women in your life will reject you as a sexist moralizer. Your daughters will feel constrained from exploring their own lives and personalities. Your sons may feel entitled to suppress and ignore women in whom they can imagine any "flaw".

But, you can similarly rationalize your characters demise.

Or, you can let your character be real to you. Let her live and be the perfect example of herself that you know well and allow the world to see. If you must kill her, let it be consistent with her life, and allow your readers to share in the pain of losing her. Let her death do something to drive the story, so that she shall not have died in vain.

If you want to show people it's a war game, maybe you play out combat situations, roll dice to see who gets shot and who lives and dies based on the situation and whose number comes up.

Literature and especially war and action fiction have had more than their share of contrived forced deaths the authors thought were good thematic ideas, but instead were mainly transparent contrived dramatically-times sacrifices. If I don't see another of those, in the rest of my days, I'll still have seen too many.

A. You don't.
B. If you have to, take the character out by surprise. Create a small plot where you are emotionally involved, if you could create a romantic scene, then when the audience is very involved in the plot, all of a sudden death arrives.

Context matters here -- if your overall tone is one of cool detachment, then you do indeed need to detach yourself, and "simply report", and let the reader supply their own feelings about the death. Those are going to be more likely tilted toward anger, pain, and resentment if the character was sympathetic. This is much harder to do well.

But if you're trying to involve the reader emotionally with your characters and want then to feel what you feel about the loss, then go ahead and feel sad and put those feelings of disappointment, loss, and grief into what you write. They don't have to be direct -- actions showing these things will work too.