Just wanted to pop in here to say that acf_remove_local_field_group is working great for me in a child theme where the parent theme defines the group in PHP.
You just have to put in a hook function that fires after acf loads like this:
function myslug_remove_my_field_group() {
acf_remove_local_field_group( 'group_example_7384' );
}
add_action( 'acf/init', 'myslug_remove_my_field_group' );
