there is certianly no official documentation, which depicts the steps needed to decommission a SCOM manageemnt group, but you also don't need one. The steps are pretty straightforward and would depend on whether you want to retain the Servers (VM) or not.
Option 1: You don't need the VMs
- Uninstall the Microsoft Monitoring Agent from all monitored systems:
o The best way would be to use some configuration management tool like SCCM for example.
o You can also uninstall those from the SCOM console in case they have been push-installed from the console.
- Simply shutdown all your VMs and delete those, including all your Management Server, Reporting Server and Gateways
- If for example you want to further use your SQL, you can only uninstall the SQL instances, holding the OpsMgr aand the OpsMgrDW databases. Of course, if you don't plan, using the SQL server/cluster then you can simple delete the nodes.
Option 2: You need the VMs/want to retain those
- The first step here is again uninstalling the agent from all managed computers (see Option 1)
- Afterwards you simple go to Add/Remove programs on each SCOm infrastructure server (Management Server, Gateway, Reporting) and uninstall "Microsoft Sysem Center Operations Manager" During the uninstall process you will be presennted with the currently installed roles (like Console, Web Console, Management Sever, etc.) and there you an just select them all and proceed with the uninstall.
- After you have uninstalled all the roles, you then can proceed with the decommissioning of the SCOM backend. Again, you can uninstall the SQL instances, which are hosting the databases.
Here is a nice summary of the process:
How to Uninstall Operations Manager SCOM
I hope I could help you with that.
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