Let's perform the following steps to remove SonarQube from your Kubernetes cluster:

1. List the SonarQube Helm releases:

$ helm ls |grep sonarqube
sonar 1 Thu Sep 26 22:01:24 2019 DEPLOYED sonarqube-2.3.0 7.9 sonarqube

2. Remove the Helm release using the release name:

$ helm delete sonar --purge

Helm will remove the SonarQube release and its components from your cluster.