First See the bellow image to understand the situation

So How you will overcome the situation as self-pickup would be free of cost. Let’s start

1. First Go to your woocommerce > Settings > Shipping tab > Shipping Zones
2. Click on the edit of the Shipping zone where you add the Delivery fee titled flat rate shipping method
3. On this specific shipping, zone add a Local pickup shipping method along with the flat rate shipping method by clicking on the Add shipping method Button
4. Finally, click on Save changes
5. See the final changes from the bellow image