The Events Calendar 4.2 // Remove "This event has passed" notice on single-event.php in a specific category

custom-notice.php

// Removes the passed event notice for events in a speicifc category
add_filter( 'tribe_the_notices', 'customize_notice', 10, 2 );
function customize_notice( $html, $notices ) {
	// If text is found in notice, then replace it
	if (tribe_event_in_category('formation-sur-demande') && stristr( $html, 'This event has passed.' ) ) {
		// Customize the message as needed
		$html = str_replace( '', $html );
	}

	return $html;
}

Hi there,

Where exactly should I add this into the single-event.php file? Do I need to change anything else?

Howdy! This can go into your functions.php file. Definitely test it out first -- this is three years old and I haven't tested it recently.

Awesome - indeed it is old, but still works! I don't (yet) see any adverse impacts either.