blender-manual/manual/animation/armatures/bones/editing/separate_bones.rst

Separate Bones

Reference

Mode:

Edit Mode

Menu:

Armature ‣ Separate Bones

Shortcut:

P

You can, as with meshes, separate the selected bones in a new armature object Armature ‣ Separate, Ctrl-Alt-P and of course, in Object Mode, you can join all selected armatures in one Object ‣ Join Objects, Ctrl-J.