You can, yes. To see how, you have to actually click on a time as if you’re placing an order. Pick the menu item, and then below it on the item screen you’ll see “customize your selection.” Click the drop down arrow to the right, and you’ll see the things you can modify. For the example you used of lettuce, there will be a blue word that says included. Click the word included, then you’ll get the option for No, thanks . Attached a screenshot from a burger from Cosmic Rays for visual explanation.