Why is Core Data shm file not removed in journal_mode DELETE?

I'm using the following code to to consolidate my Core Data sqlite store files, which current consists of the database itself, a -wal and a -shm file. I am doing this so I can manipulate it as a single file using NSFileManager.

NSPersistentStoreCoordinator *tmpPSC = [[NSPersistentStoreCoordinator alloc] 
      initWithManagedObjectModel...];

NSDictionary *options = @{NSSQLitePragmasOption: 
                        @{@"journal_mode": @"DELETE"}};

NSPersistentStore *persistentStore = [tmpPSC 
   addPersistentStoreWithType:NSSQLiteStoreType configuration:nil 
   URL:storeURL options:options error:NULL];

if (persistentStore) {
   [tmpPSC removePersistentStore:persistentStore error:NULL];
   tmpPSC = nil;
}

However, after the above code execute, I am seeing the -wal file disappear, but the -shm file is still there.

Any idea why this is so?