The asynchronous task concept is core to the REST API and how APIC-EM functions. The basic pattern is to take the taskId from a request response, and then use the task API to check task status. Presuming that the system does not keep tasks around forever though, as that would bloat the database.want to know how long does a taskId remain valid.
With the current implementation, the task id's are kept for forever and we don't purge it. Most likely need to add an expiry timer to purge in the future releases. Don't see any API to delete task.