I am having the same issue and have found no solutions. It is a little absurd that there is not a way to do this. If you add a separate location for "pickup only" items like I saw someone suggested in another post, it still shows the shipping option on the checkout page. You would think this would be a priority for Shopify in this day and time. The only way I am seeing to be able to do this is to purchase yet another app which is very frustrating.