I need to cancel the form submission based on an answer

If I have an option near the beginning of the form that has a yes/no answer, I would like to cancel the completion of the form if the answer is no. Can this be done?

You can always use conditions to hide submit button (for example) if No is selected. You could also just hide the rest of the fields - besides the submit button, but as soon as you hide the submit button, the form can not be submitted any more.

Please do take a look at the following guide for more details: Smart Forms Using Conditional Logic and of course if you have any questions just let us know :)