<p>I am installing prometheus to monitor K8S but I met this error. 
Can you help me?
Thank you so much!!</p>

<pre><code>helm version
Client: &amp;version.Version{SemVer:"v2.13.0", 
GitCommit:"79d07943b03aea2b76c12644b4b54733bc5958d6", GitTreeState:"clean"}
Server: &amp;version.Version{SemVer:"v2.13.0", 
GitCommit:"79d07943b03aea2b76c12644b4b54733bc5958d6", GitTreeState:"clean"}

helm install stable/prometheus-operator --name prometheus-operator --namespace monitoring

Error: customresourcedefinitions.apiextensions.k8s.io "alertmanagers.monitoring.coreos.com" is forbidden: User "system:serviceaccount:kube-system:default" cannot delete resource "customresourcedefinitions" in API group "apiextensions.k8s.io" at the cluster scope
</code></pre>

<p>This is a typical situation when Tiller (server side of Helm setup) is deployed without a service account having appropriate cluster role (cluster-admin).</p>

<p>You need to fix your Helm setup first, to be able to proceed with prometheus-operator installation, as described <a href="https://helm.sh/docs/using_helm/#tiller-and-role-based-access-control" rel="nofollow noreferrer">here</a>, or by running the below commands directly one by one:</p>

<ol>
<li><code>kubectl create serviceaccount --namespace kube-system tiller</code></li>
<li><code>kubectl create clusterrolebinding tiller-cluster-rule --clusterrole=cluster-admin --serviceaccount=kube-system:tiller</code></li>
<li><code>kubectl patch deploy --namespace kube-system tiller-deploy -p '{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}'</code></li>
</ol>
