Error The computer “servername.domain” is joined to a cluster on Windows 2008 R2

In the case that a Windows 2008 R2 node was previously active in another cluster, you may experience a problem when adding that node to the new cluster. The following error could occur:

The computer “servername.domain” is joined to a cluster.
 

The easiest solution would be to disjoin the server from the cluster. To do so, open the Failover Cluster Manager in our Server Manager, right-click the node you want to add to the new cluster, and click Evict.

However, it may be the case you already did this. In that occasion, you may need to disable the Cluster service. When you add a node to a cluster, the cluster service is set to start Automatically. To disable the Cluster Service

• Open services.msc and set the Startup type of Cluster Services to Disabled, OR
• Start powershell and type
  get-service -Name "Cluster Service" | Set-Service –StartupType Disabled

This should help 🙂