$ time kubectl delete rs my-first-replicaset && kubectl get pod
replicaset.extensions "my-first-replicaset" deleted
real  0m2.492s
user  0m0.188s
sys   0m0.048s
NAME                        READY     STATUS        RESTARTS   AGE
my-first-replicaset-8hg55   0/1       Terminating   0          53m
my-first-replicaset-b6kr2   1/1       Terminating   0          48m
my-first-replicaset-wtphz   0/1       Terminating   0          53m
my-first-replicaset-xcrws   1/1       Terminating   0          53m

Removing the Pod under ReplicaSet
As we mentioned previously, it is impossible to scale down the ReplicaSet by deleting the Pod, because while a Pod is removed, the ReplicaSet is out of stable status: if the desired number of Pods is not met, and the controller manager will ask ReplicaSet to create another one. The concept is shown in the following commands:

// check ReplicaSet and the Pods
 $ kubectl get rs,pod
 NAME DESIRED CURRENT READY AGE
 rs/my-first-replicaset 3 3 3 14s
 NAME READY STATUS RESTARTS AGE
 po/my-first-replicaset-bxf45 1/1 Running 0 14s
 po/my-first-replicaset-r6wpx 1/1 Running 0 14s
 po/my-first-replicaset-vt6fd 1/1 Running 0 14s
 
 // remove certain Pod and check what happened
 $ kubectl delete pod my-first-replicaset-bxf45
 pod "my-first-replicaset-bxf45" deleted
 $ kubectl get rs,pod
 NAME DESIRED CURRENT READY AGE
 rs/my-first-replicaset 3 3 3 2m
 NAME READY STATUS RESTARTS AGE
 po/my-first-replicaset-dvbpg 1/1 Running 0 6s
 po/my-first-replicaset-r6wpx 1/1 Running 0 2m
 po/my-first-replicaset-vt6fd 1/1 Running 0 2m
 
 // check the event log as well
 $ kubectl describe rs my-first-replicaset
 (ignored)
 :
 Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal SuccessfulCreate 2m replicaset-controller Created pod: my-first-replicaset-bxf45
 Normal SuccessfulCreate 2m replicaset-controller Created pod: my-first-replicaset-r6wpx
 Normal SuccessfulCreate 2m replicaset-controller Created pod: my-first-replicaset-vt6fd
 Normal SuccessfulCreate 37s replicaset-controller Created pod: my-first-replicaset-dvbpg

You will find that although the my-first-replicaset-bxf45 Pod is removed, the my-first-replicaset-dvbpg Pod is created automatically and attached to this ReplicaSet.