PeepSo Docs

Disable All Email Notifications

Administrator can decide whether email notifications are ON or OFF by default for new members. You can set that in the backend of your site. Navigate to WP Admin -> PeepSo -> Configuration -> Advanced
Locate the Email panel and find Don’t subscribe new members to any e-mail notifications option.
Set it to Yes and all new members will have their e-mail notifications disabled by default.

This setting does NOT affect any onsite notifications.

Disable All Notifications for a Single user

Administrators can disable ALL e-mail notifications for a given user. You can set that in the backend of your site.
Navigate to WP Admin -> Users
Click Edit user you want to disable their E-mail notifications and then find: Unsubscribe this user from all e-mail notifications
Click, and that user will have their e-mail notifications disabled.

This setting does NOT affect any onsite notifications.