After setting up business services (which is pretty slick BTW) how do I clear out the data from the setup period so that my percentages are correct?
There's no option to clear history from the GUI, but you can delete data from database.
You need to stop server process prior to deleting from the DB!!!
The table you need are these two: BUSINESS_SERVICES_DOWNTIME, BUSINESS_SERVICE_TICKETS. First keeps downtime records, second keeps tickets which are displayed at the bottom when viewing a business service.
Document describing the DB is here:
https://www.netxms.org/documentation/datadictionary-latest/#t-business-services-downtime
https://www.netxms.org/documentation/datadictionary-latest/#t-business-service-tickets