Hello @wpgsander,
Unless you’re comfortable modifying your database there isn’t a way to delete a single customer or order from the analytics tables.
If you’re OK with deleting and reprocessing all analytics data, it’s possible to clean up these now deleted test customers and orders. Go to Analytics > Settings, scroll to Import Historical Data. Click “Delete Previously Imported Data”. When that process is finished, the status should read “Ready to Import” and you can click “Start” to re-import your data.