If you’ve completely botched this up, there are a few things you can do:
1.) The easiest method is to go to your website FTP, locate your wp-content folder > plugins and completely delete your PHPBB bridge plugin
and/or
2.)If you need immediate access to wp-admin then all you need to do is FTP into your WordPress plugins directory and rename the wp-phpbb-bridge plugin folder to something else. You’ll be able to access wp-admin once again.
The problem however is that the bridge function of the plugin is still enabled in MySQL… Here’s the fix for that…
Login into phpMyAdmin from your CPanel and open your WordPress database. Search for wpb_active and select all the DB tables before clicking Go. You’ll now see the row wpb_active, click on edit. Change both “yes” values to no. You now have your wp-admin back!
hope this helps and isn’t too confusing. Good luck!