You have an Azure Databricks workspace that is enabled for Unity Catalog.

Two actions are needed to reclaim storage while keeping tables queryable:

Set delta.deletedFileRetentionDuration and delta.logRetentionDuration to 90 days on each table. These properties define the retention floor — VACUUM will not touch anything newer than this threshold, so no data needed for time travel within 90 days can be accidentally removed.

Run VACUUM on each table. VACUUM is the Delta Lake command that physically removes data files and transaction log entries older than the retention duration. Importantly, VACUUM runs as a background operation — it uses Delta Lake ' s MVCC (multi-version concurrency control) to ensure that concurrent reads against the table continue uninterrupted while cleanup happens. Tables are fully available throughout.

OPTIMIZE compacts small files for query performance but doesn ' t delete anything. Manually deleting files outside the Delta protocol would corrupt the table.