Because it’s their forum/place of (unregulated) business and they can delete whatever they want. Or OPs can delete their own threads anytime normally anytime they want. Best to ask the only people who could give you an answer if needed ie the moderators, if desired, but I would expect they are under no obligation to explain such things to anyone if they choose not to. It’s a free forum that serves a business purpose so consider using it a privilege not a right.
Why this forum deletes full threads ?
Can anyone explain why the administrators of this forum deleted the “users with hidden agendas?