Drupal Commerce: How to disable or unlock Off-site payment redirect? How to eliminate checkout page "Payment"?

I am using Drupal Commerce and since we have offline payments after checkout I would like to disable the extra step "Payment" in the checkout process which is reserved for "Off-site payment redirect". You might argue that this is not needed, because this step is eliminated when having no payment methods. That's true, but it is still displayed as a step in modules such as "Commerce Checkout Progress" and as such showing a step to the end-user which dies in fact does not exist.

I did not find a way to disable this directly in the UI at Checkout settings (admin/commerce/config/checkout) because this checkout pane seems to be locked.

So I digged in code and found line 309 to 315 in commerce_payment.module (\modules\contrib\commerce\modules\payment\commerce_payment.module).

$checkout_panes['commerce_payment_redirect'] = array(
'title' => t('Off-site payment redirect'),
'page' => 'payment',
'locked' => TRUE,
'file' => 'includes/commerce_payment.checkout_pane.inc',
'base' => 'commerce_payment_redirect_pane',
);

If I completely remove these lines the payment step is gone. If I set the locked value to "FALSE" I can disable the pane at Checkout settings. Then the step is eliminated from "Commerce Checkout Progress" and as such shown correctly to the end-user.