User Data Deletion

User data deletion is the removal of every record linked to one identified person from a system, either on that person's request or on a retention schedule.

A deletion request only means something where records are linkable to a person, so the first step is resolving every identifier that person owns: the account ID, the anonymous device IDs, the session IDs and anything derived from them. Deletion then has to reach three places that are easy to forget: pre-aggregated tables, exports already pushed to a warehouse or a third party, and backups. Deletion is not anonymisation, because once the link to the person is irreversibly broken the aggregate history can lawfully remain, and that is how most products avoid tearing holes in past reports. The recurring mistake is promising instant erasure, since analytical storage is usually append-only and needs a scheduled cleanup pass, so an honest policy states a maximum window instead.