Kubeadm upgrade process

Hii all,
Please tell me the step by step procedure to upgrade the control plane node from v1.21.0 to v1.21.1.Please tell how to upgrade a patch version of a cluster. I’m getting error as “Are you root”. Please tell the steps to upgrade.

@Annamalai , You may need to use sudo command or switch to root user. Check the steps from the official documentation.

Yes sir, First I drained all the pods in the controlplane. Then I logged into master node and completed the ```
apt update
apt-cache madison kubeadm

While trying to upgrade Kubeadm, it is showing "Error, Are you root." What is the problem behind it..