Currently, there’s no way to disable email notifications sent to users when being added to a team.
This feature would allow us to define whether to send or not notifications, could be implemented in the invite modal or could be a site-wide feature.

Team-related actions that generate a notification include:

• Adding a user to a Team
• Deleting a Team

Workaround:

Remove non-admin users from the Teams; performing a deletion should not trigger a notification to all the users except admins