Currently, it's not possible to disable feature called Confluence Recap at the site level.

At the user level, each user has the option of unsubscribing from the Confluence Recap emails for future iterations. This can be done from their own personal user email settings by:

1. Navigating to Personal settings under their profile icon in the top-right corner
2. And in the section Email, edit and uncheck the option Confluence Recap emails from the Summary reports section
3. Submit the change

Example below: