Immediate Insight automatically ages out and removes records that are older than TTL, the TTL is configurable per collector.
However if you later reduce the configured TTL for a collector, Immediate Insight does not retroactively go back and delete the older records (which were still valid under the old TTL setting).
To delete this older data, you can choose a Custom Time Period in Search, then Click Search, then Delete Result Records from the results to bulk delete old records that are already in the system under a different TTL. For example to delete data between 14 and 7 days old:
You can also Search for certain types (Search strings) of data you are no longer interested in (e.g. informational records), and Delete these Result Records.