I recently ran through an issue where i wanted to automatically delete snapshots after 5 days instead of the default 7 days that comes out of box in automation central. I wanted to change delete old snapshot restriction from 7 days to 5 days.
It seems like the restriction comes from the Reclaim Settings. In order to change it we can go to Optimize -> Reclaim -> Settings
Change the Snapshots setting to older than
Going to Automation Central i was able to confirm that the minimum is now 5 days