Hi check_mk_user and welcome to the forum,
you can disable notifications for host and services by activating a rule.
Go to WATO - Configuration - Host and Service Parameters. In the search field type disable.
No you can create a rule ‘disable notifications for hosts’ or ‘disable notifications for services’
Now no notifications are creating.
You can find out more information about notifications in the manual: https://checkmk.com/cms_notifications.html#Disabling%20notifications%20using%20rules
Hope it helps
Regards
Anastasios