There are various reasons for decommissioning a Citrix XenApp 6.5 server e.g. you have upgraded the Citrix Environment to 7.X or the product is end of life or it could be to save the cost of running and maintenance of the old servers. But before you do, make sure all the Application and Server Dependencies are taken in to account and migrated to the new servers.
Here is a list of steps which you can use to decommission a Citrix XenApp Server. Its a very basic and generic checklist which should be applicable to most of the Citrix XenApp 6.5 Environments.
> Uninstall Applications from Citrix XenApp Server e.g Sage, Microsoft Office, Adobe Acrobat or any other Licensed application so as to DE-register or release the application license to be re-used.
> Uninstall Anti-Virus from the Citrix XenApp Server which will remove the entry of the server from the Anti-Virus Management Console. If you are using the Cloud Anti-virus, it will contact the Cloud AV Management and removes the Entry of this server from its database. (Please check it once and if its not removed, Please remove it manually).
> Uninstall Citrix XenApp and all other components of Citrix from that Server. Go to Start -> Run -> Type appwiz.cpl to open the List of Applications Installed on the server, Select the Citrix Components one by one and Uninstall. You can also use Citrix XenApp Role Manager if required to remove the server from Citrix Farm.
Once All the Citrix Components have been uninstalled from the server, Please check if the server is still showing on the Citrix Farm. If yes, then delete the server from the Citrix App Center company Citrix Farm and make sure its not a member of Worker Groups.
> UN-join the Citrix Server from AD Domain and delete its computer account.
Check if there are any DNS records for this server. Delete the DNS Entry of this server from AD Integrated DNS Server.
> Shutdown the server and monitor it for few days before complete removal from Disk.
> Update the Documentation.