Download your existing htaccess file and edit it and then upload it back to your site. Add this generic WordPress Rewrite code below and any other code that you want to add into the htaccess file. If you do file backups then grab your last root htaccess file from a backup or if your host does file backups then restore it from your host file backup. If you deactivate and delete the BPS Pro plugin on the WordPress Plugins page then that removes all BPS Pro files and database settings.
<IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L] </IfModule>