Disable shipping address option in PayPal Express Checkout

Working with the PayPal API and using the Name-Value Pair Interface PHP source codes from SDKs and Downloads: Simplify Integrations with Downloads and SDKs.

My question is similar to "Removing (or prefilling) the address details for PayPal Express Checkout" but I don't want shipping cost/address or anything related about shipping at all.

I keep all shipping details on my system (even sometimes shipping doesn't even apply and there is no charge for it) and I just want user to pay through PayPal without shipping address and shipping cost.

How can I disable shipping part of checkout?