Drop outdated link to v1.6 upgrade

content/en/docs/tasks/administer-cluster/cluster-management.md

@@ -26,8 +26,6 @@ To install Kubernetes on a set of machines, consult one of the existing [Getting
 
 The current state of cluster upgrades is provider dependent, and some releases may require special care when upgrading. It is recommended that administrators consult both the [release notes](https://git.k8s.io/kubernetes/CHANGELOG.md), as well as the version specific upgrade notes prior to upgrading their clusters.
 
-* [Upgrading to 1.6](/docs/admin/upgrade-1-6)
-
 ### Upgrading an Azure Kubernetes Service (AKS) cluster
 
 Azure Kubernetes Service enables easy self-service upgrades of the control plane and nodes in your cluster. The process is