In recent versions of Splunk Enterprise (at least from 7.1), there is a pre-built dashboard in "Search and Reporting" app named "Orphaned Scheduled Searches, Reports, and Alerts". This shows the saved scheduled searches, reports, and alerts with deactivated owners. If you want to schedule it, simply copy the SPL powering the dashboard and schedule it. In my Splunk, here is the search powering that dashboard.
| rest timeout=600 splunk_server=local /servicesNS/-/-/saved/searches add_orphan_field=yes count=0
| search orphan=1 disabled=0 is_scheduled=1
| eval status = if(disabled = 0, "enabled", "disabled")
| fields title eai:acl.owner eai:acl.app eai:acl.sharing orphan status is_scheduled cron_schedule next_scheduled_time next_scheduled_time actions
| rename title AS "search name" eai:acl.owner AS owner eai:acl.app AS app eai:acl.sharing AS sharing
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