Sufficient for what? If you're sure of those things you mention, you can delete the *-wal and *-shm file. But if you're incorrect and delete them, the database may become corrupt. If you use the shell tool to clean up the *-wal and *-shm files, it will simply delete them if the *-wal file really is empty and unused. But if it is not, then the shell tool will not corrupt the db. So usually it's better to do it that way.