Admins can configure user notifications for events from their settings. By default all the notifications are enabled for all the fylers when an organisation is created. To alter any of the notifications you can navigate to Settings > Organisation > Notifications.
The notifications are categorised in three sections -
Expenses and Reports
To disable any of the notifications, you can just uncheck the box corresponding to the respective notification and click on save.
Note: Any changes made on this page will apply to all the users in the organisation.