How to disable billing address in Drupal Commerce while using Paypal WPS
If you do not need Billing Address section at all, it should be as simple as dragging Billing Information under disabled from any of checkout/review step. 
Go to page 'admin/commerce/config/checkout' in order to disable Billing Section.

If you want Billing Address section to vanish conditionally based on payment method opted(in case you have multiple way of payment) then it is already answered here by Ryan himself.