dbunload utility for SEP 12.1
Since the dbunload utility doesn't support Symantec Endpoint Protection 12.1 the workaround is, use SEP backup and restore utility to shrink embedded database.
Symantec Endpoint Protection 12.1: Best Practices for Disaster Recovery with the Symantec Endpoint Protection Manager
Unfortunately, this procedure did not reduce the size of the database. In my case, the size increased from 5 GB to 7.5 GB.
The data base maintenance didn't changed the size after a few cycles.
If a tool can be created like dbunload, it would be much appropriate.