where can i configure the cancel button

I use apple sign on web using the URL

https://appleid.apple.com/auth/authorize?response_type=code%20id_token&client_id=com.outblaze.mindfuloceanmeta-siwa&redirect_uri=https://api.mindful-ocean.org/mindfulapi/appleauth&cancel_uri=https://www.yahoo.com&state=5f510c9e6b&scope=name email&response_mode=form_post

when it comes to this stage and press "cancel", it redirect me to an invalid url. Where can i configure the URL for the cancel button?

where can i configure the cancel button
 
 
Q