This can be done by searching for a customer and going to the "View Details" screen (or just click on the customer box at the top of the virtual ticket).
Expand the 'Order Types' section which is at the bottom, middle of the screen.
Here you can uncheck any order types that are not valid for this customer.
Note: This will not prevent online orders for this customer. Another way to block a customer from delivery (which will work online and in the POS) is to create an "Invalid Delivery Address". Navigate to Thrive Control Center by clicking on Home > Manager > Control Center, then go to Configuration > Delivery. You'll need to select a particular location. Scroll to the Invalid Addresses section and choose Add.
Here, you can add an individual address. The system will validate that it is a proper address. Add a note so you will remember why it is bad.
Save and publish these changes. Now, any customer who enters this address will find it to be out of your delivery area.