I want to remove “Armature.010” without removing bones assigned to it (“Hips”, “spine” etc). Is it possible?
Why do you want to do that?
An armature is an organizational concept: a container that holds bones, a place to specify variables that affect every bone in that container.
You could certainly separate all of those bones to individual armatures. But you’d still have armatures for each of those bones. And it would, almost without a doubt, be a terrible idea.
I need to separate this because I can’t put animations on this rig in Unity
The fact that you have an armature object is not the reason you can’t put animations in Unity. Something else is happening. You might consider asking around on Unity forums.