How would you do a data cleanup in BPC 7.5 MS 2k8 version

Hi

I am new to SAP BPC 7.5  sp8 MS version.We would like to do a data cleanup.By this I mean remove records that are no longer relevant,due to major changes in the company.We can have them on DEVELOPMENT server, simply for reference purposes,but we would like to have a clean database moving forward into the new year and new environment we are moving to.