BuddyPress.org

Here are the steps to create a user blog theme off of the BP default theme:

1) Create a new child theme.

https://codex.buddypress.org/how-to-guides/building-a-buddypress-child-theme/

2) Copy over /plugins/buddypress/bp-themes/bp-default/header.php to your child theme’s directory.

3) In your child theme’s header.php, strip out all the [li] items in the [ul id=”nav”] block as well as the do_action line. Leave the wp_list_pages() line intact.

4) That’s it! Your new theme is ready to be used on user blogs