Set Custom Appointment Cancel Link

Custom Cancel Link.php

add_action('app_confirmation_message', 'custom_cancellation_link' , 1 , 2 );
add_action('app_reminder_message', 'custom_cancellation_link' , 1 , 2);

// Hooks really early and replaces the cancel link 

	function add_cancel_link( $text, $app_id ) {
	   // Put your link here
	   $link = 'www.example.com/cancel' ; 
	   
		return str_replace( 'CANCEL', $link , $text );
   }

Just copy/paste the code into the functions.php file of your child theme or a site specific plugin if you use one. Remember to replace the $link variable with the Cancel Appointments page