No Yoast on Events? can’t set to no-index

There are no Yoast settings on the individual events pages. I am trying to set past events to no index. I tried the code offered here https://gist.github.com/joshfeck/70979dc12f93ab25dd668ed4500be477 but it is not working. I can see the event is still set to follow. This is causing an issue because Google is indexing them. How can I get either Yoast to show or is there updated code to prevent past events from being indexed?
thanks