To add a Decline button to your response form and send an automatic decline email to your guests, you need to click on the 'Decline Options' tab inside the Form Builder and toggle this function from 'OFF' to 'ON'.
You can then turn on the email feature by toggling 'Send Decline Email' to 'ON' as a second step:
Once the Decline Email feature has been switched on, you will also see it appear as an additional section at the bottom of your browser screen:
The Decline Email allows for the same customization as the Invitation and Confirmation Emails. However, please note that you can choose to include different information and email addresses in the Settings tab for these different email types. You might also want to customize the content of your emails (images and text) differently to match their individual purposes.
For further instructions on how to complete the Email Setup and customize the email content via the Email Builder please see this article here.