What database do you use?
The problem of unique constraints for soft deleted entities is solved automatically on PostgreSQL, SQLServer and Oracle, and a solution for MySQL is described here. HSQL has the same difficulties as MySQL, but as we consider it only for prototyping purpose, we don’t provide a solution yet.
As for permanent deletion of soft deleted entities, there is no built-in mechanism for this. So if it is a one-time problem for you, just remove records directly from the database. If you need a UI for this operation, create a browse screen for your entity and set softDeletion=“false” attribute for the datasource in screen’s XML. Then the datasource will propagate this flag to DataManager when it loads and commits entities.