There is no admin switch for that.
And, since it's a templating change you want to make site-wide, it really belongs in the template anyway.
edit /includes/templates/YOURTEMPLATE/common/tpl_main_page.php
you see this:
Code:
// the following IF statement can be duplicated/modified as needed to set additional flags
if (in_array($current_page_base,explode(",",'list_pages_to_skip_all_right_sideboxes_on_here,separated_by_commas,and_no_spaces')) ) {
$flag_disable_right = true;
}
On a new line above that, add this:
Code:
$flag_disable_header = true;