If your customer wants to change the site title you can send this Function.php code. First, could you ask the customer to change it through WordPress Dashboard - Appearance - Site Identity? 

If the customer could change the title and there is still "WordPress" showing, You can use the following function code. Please see the steps below:

Note: Make sure to have a complete site backup before proceeding

1. Go to Appearance > Theme Editor.

2. Under Select theme to edit, choose (BuddyBoss Child/whatever theme is active), then click Select.

3. Below Theme Files, select Theme Functions (functions.php).

4. Append the code just before the closing PHP tag “?>”:

function custom_login_title( $login_title ) {
return str_replace(array( ' ‹', ' — WordPress'), array( ' ‹', ''),$login_title );
add_filter( 'login_title', 'custom_login_title' );

5. Click Update File to save the changes.

Note: Any modifications are considered as custom work already. Know more about our Support Policy here: https://www.buddyboss.com/support-policy/