In the BSI UI, go into the report list and click the pencil next to the report in question to edit it.
Scroll down to the bottom and edit the schedule. This will contain the list of addresses that scheduled report is being sent to.
If you want to find all the scheduled reports that are being sent to a particular address, you can run:
select report_name from t_report_galleries rg, t_schedules s where rg.schedule_id=s.schedule_id and upper(task_info) like '%EMAIL_ADDRESS_IN_UPPERCASE@SOMETHING.COM%'