There are two options for disabling submitting users from receiving copies of the reports they make.

Each user has their own Profile settings, so if only certain staff want to disable this, they can disable notifications for themselves - Edit your User Profile in the Web Portal - Safe365

Or in some cases, you may wish to have staff no longer receive a copy of reports they make at the Organisation level.

There is a global setting within the Organisation Profile, called 'Instant PDF Reporting' to enable, or disable, the submitting user from receiving copies of the reports they make - Update your Organisation Profile - Safe365