Not sure best way to clear them out, as you would have to login as the user who created the scheduled report.
This is done in CCMWeb > Reports > Scheduled Reports.
There's a table in SQL DB CCMData that has all the scheduled reports I believe. dbo.tblReport_Schedule
I just did a quick test and not sure if this will break anything else, but I deleted an entry from SQL directly and it disappeared from my scheduled reports.
