How to disable shipping methods by product?

Hello all,

I’m new to web work, but have been poking through a new e-commerce site for my business. I’m using Woocommerce and ran into a snag. I am running the USPS and UPS plug-ins to calculate shipping. This works for most products, however, there are a few products that get drop shipped to the customer and only go via UPS. I would like to disable USPS shipping options when certain items are present in the cart. How can this be done?

I don’t have a link to the site, yet. Still working locally…