You can turn the option for Delivery or Pickup off or on at any point.
To do so:
Head to your stores page page in the right hand bar
Enter your Store Settings
Enter the Operations settings
The “delivery” / "pickup" box can be ticked or unticked
It’s still not working?
If you find that this hasn’t worked, it’s likely to be one of the following two reasons:
You just need to turn on “accept orders” (read article)
Your opening times are the problem. Opening times can be found in the opening hours tab to the left of settings. (read article)