Re: A bit of advice needed
If you are installing fresh, sure, just delete those. If you want, you can change the table prefix in your new bbpress installation. I forget where it is in the installation procedure, but maybe it’s under an option called “advanced database settings” or something? I think it was hidden unless you reveal it by clicking.
If bbPress finds the bb_ tables there already, I suspect it might just try to upgrade the database. That’s probably OK, but if you don’t need the old bbPress installation, I would just start from scratch with new tables.