Tag historian delete old data

from the manual:
How SQLTags Historian Works
SQLTags Historian gives you the ability to quickly and easily store historical data for your tags, and provides efficient querying of that data. Options for partitioning and deleting old data help ensure that the system stays properly maintained with minimal extra work.

How can Ignition automatically delete older records from the historical data tables?

This is configured under your SQLTags Historian in the gateway. Ignition deletes old data by deleting old partitions.