General

The MotionSystem group contains the FK and IK animation controllers.
Delete MotionSystem
Delete the MotionSystem while keeping the basic skeleton DeformationSystem.
Deletes the MotionSystem.
The MotionSystem is all the FK and IK animation controllers.
After deleting the MotionSystem, you will still have the basic skeleton (DeformationSystem).
Then you can use another system to drive the skeleton, such as HumanIK.

Tip: Use this when another animation system, such as HumanIK, will drive the DeformationSystem.