Notifications are sent to all users with the organization ROLE_ADMINISTRATOR role, who belong to the same organization as the user who creates the scheduled job.
There are 2 resolutions:
1. Remove the ROLE_ADMINISTRATOR for the users receiving the notification
(unless ROLE_ADMINISTRATOR is needed)
Go to resource and remove from Clarity resource right (Advanced Reporting - Administer)
2. Do not notify users on job success or failure by unchecking the option
https://community.jaspersoft.com/documentation/jasperreports-server/tibco-jasperreports-server-user-guide/vv900/jasperreports-server-user-guide-_-schedules-_-schedules-notifications/