Open /admin tools, Open "Run php command", follow instructions to enable this. Then execute
$tab = 'aaaaaaaxxxxxx';
Utils_WatchdogCommon::unregister_category($tab);
DB::DropTable($tab.'_callback');
DB::DropTable($tab.'_recent');
DB::DropTable($tab.'_favorite');
DB::DropTable($tab.'_edit_history_data');
DB::DropTable($tab.'_edit_history');
DB::DropTable($tab.'_field');
DB::DropTable($tab.'_data_1');
DB::DropTable($tab.'_access_clearance');
DB::DropTable($tab.'_access_fields');
DB::DropTable($tab.'_access');
DB::Execute('DELETE FROM recordbrowser_table_properties WHERE tab=%s', array($tab));
DB::Execute('DELETE FROM recordbrowser_processing_methods WHERE tab=%s', array($tab));
DB::Execute('DELETE FROM recordbrowser_browse_mode_definitions WHERE tab=%s', array($tab));
DB::Execute('DELETE FROM recordbrowser_clipboard_pattern WHERE tab=%s', array($tab));
Don't mess with database if you don't know what you're doing :!: