You are welcome! I'm still learning and trying my best to provide better support here.
When you click remove to remove the installed PHPBB, it will automatically remove the files. It will not remove the database. To remove the database, go to Goodies --> Manage MySQL
When you install it again, I'll suggest to install it in a different folder and create a particular database for it so that it won't mess anything up
Save [color=#CC0000]$97[/color] (max discount) on dreamhost by using promo code: [color=#CC0000]97CRAZY[/color].