Hide billing address in front office (not delete) PS 1.7.7.3

[Butigon]

Hello, I need to hide the billing address from the front office checkout and in any case leave it the same as the delivery address by default. We do not want to make these fields disappear neither from the email nor from the pdfs, only that the customer does not have the option of entering the billing address while he is processing an order on the page. We want to leave the ability to get an invoice only from administrators from the back office when our customer want a different billing address. Thanks.