Hi Ian,
There are some Appworx process flows you should be running if you are not. The SYSTEM process flow will purge history to the number of days you specify. I believe this one gets enabled by default with an upgrade, but the prompt for days is on the HISTORY_PURGE component. You can also purge audit data with the PURGE_AUDIT_HISTORY job. Details for that are here:
https://techdocs.broadcom.com/us/en/ca-enterprise-software/intelligent-automation/applications-manager/9-4-0/Administration_Guide/Working_with_the_Automation_Engine_and_Agents/Enabling_Applications_Manager_Auditing.html
Jim