Overall, this is intended to be a semi-manual process that runs every quarter or so. If you really want to automate, the email portion can be set on a schedule once VizAlerts is set up. You'd need to script out the executions for the commands to archive and delete content, though.
The delete command does not work in case of nested workbooks / datasources. Can I please ask you if you have figured any workaround for this scenario ?