Why is this needed? As a policy, Tiki doesn't delete data without a site admin's consent/knowledge. So when a feature is removed, what do we do with the associated data? Database tables are renamed to make it easy for an administrator to review and delete manually (or keep/move/etc.). However, preferences (configurations) are just kept in the database. So a tool like Adminer is needed to check for data and delete it. But it's tricky to what which data is no longer used. This feature permits Tiki admin to review and delete.
As of Tiki25, please consider this feature as experimental. Only use it if you are an experienced Tiki administrator.
There is likely some data here that is actually still used, but in a non-standard way, so it fools our script.