Please visit this page for more details on how to install kubectl: https://kubernetes.io/docs/tasks/tools/install-kubectl/

• Check if any update:
  $ sudo apt update
  
• [Optional] Install packages to allow apt to use a repository over HTTPS:
  $ sudo apt install \ apt-transport-https \ curl
  
• Download kubectl:
  $ curl -LO "https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl"
  
• Make kubectl executable:
  $ chmod +x ./kubectl
  
• Move kubectl to /usr/local/bin/:
  $ sudo mv ./kubectl /usr/local/bin/kubectl
  
• Verify kubectl:
  $ kubectl version --client Client Version: version.Info{ Major:"1", Minor:"18", GitVersion:"v1.18.6", GitCommit:"dff82dc0de47299ab66c83c626e08b245ab19037", GitTreeState:"clean", BuildDate:"2020-07-15T16:58:53Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64" }

• Remove kubectl:
  $ sudo rm -f /usr/local/bin/kubectl
  
• [Optional] Remove kubectl configuration folder:
  $ rm -rf ~/.kube/