How delete billing address fields on contributing page?
As Christia points out, online credit card processing requires an address, so you can't get rid of them. 

If your goal is to simplify as much as possible that form, your best strategy would be to not include any profile fields, and then the form would just include the built-in billing fields.

If you do find a payment processor that will work without address fields somehow, then in theory a plugin could be written that would replace those billing fields with different ones. Who knows? It might not be long until you can just put in a mobile phone number instead and it'll look up your information somewhere ...