Will it be possible for you to provide SQL to delete Topics (along with posts), where TAG is like '%unsafe%', please?
Yes, it's possible. Here is the SQL. Just replace wp_ table prefix if it's different for your WordPress database.
DELETE FROM `wp_wpforo_topics` WHERE `tags` LIKE '%unsafe%'
After executing this SQL, go to Dashboard > Forums > Dashboard admin page and click these buttons:
- Delete All Caches
- Update Forum Statistic
- Update Topic Statistic
- Update User Statistic
- Delete All Caches (again)