Auto Scaling - ESS - AutoScaling supports DetachInstance
Target customers: all customers Features released: to detach one or more ECS instances from one scaling group. After the ECS instance is detached, it can exist independently of the scaling group, and you can attach the ECS instance to another scaling group (AttachInstances). Detaching an ECS instance does not stop or release it. If necessary, you can manually stop or release the ECS instance.