How to Un-install a clustered instance from SQL Server 2008 R2 cluster?

We have a 2 node cluster(Active/Passive) and has 2 SQL Server 2008 R2 instances running. We need to Un-install one of the running instance from this cluster.

Normal SQL Server Un-installation we can do directly from Add/Remove programs of Windows server but to perform the same in cluster environment is bit different.

For removing clustered instance first we need to copy the set up files of SQL Server to local drive of Passive node and run ‘Setup.exe’.

Select ‘Maintenance’ option in the below window and click on ‘Remove node from a SQL Server failover cluster’

 this will start ‘Setup Support Rules’ window:

This will verify all the required rules and will give detailed report:

If any failures noticed, need to fix them before proceeding further. 

Next window will show available cluster nodes and SQL instances currently running:

Make sure correct instance is selected in ‘SQL Server instance name’ section. We need to select the instance (in the highlighted section below) name which we want to remove from cluster 

after clicking on next it will shows us the currently installed features of selected instance:

To start removal of instance click on ‘Remove’ button. Removal process will start:

Once instance removal completes, re-start the passive node. Now login to the active node and follow the above same steps. After removing the instance from Active node we need to reboot the active node as well to complete the Un-installation.

Note: Before rebooting current Active node make sure to failover the other running instance of active node to the passive.

Thanks!!