Deleting old Promotions from the Promotion Management programmatically

Due to disk space issues, I would like to delete promotion jobs(mainly backup jobs) older than a certain date (15 days) for a SAP BI 4.1 platform. At the moment I do this manually once a week, but is there a way of automatizing this process, either by an automatic process in the CMC, or maybe using the RESTful API or the CrystalDecisions.Enterprise libraries?

Thanks,

Enrique