Completion workflows control what happens after a change request is fulfilled. You can configure a distinct completion workflow for each of your change request forms. Conditional workflow steps and variables provide considerable flexibility. Variables also permit access to information captured during the request process.
Are some of your user groups experienced enough to manage their own self-service? For example, in a lab environment, administrator approval likely isn't necessary for actions by a testing group that regularly decommissions its own services.
Use completion workflows to automate the most error-prone and time-consuming tasks.
You can use a decommissioning workflow to power off a VM and delete it from disk.