Example of how to filter the calendar event time to remove the times if you have a hide-event-times custom field set on the event.

tw_ee_filter_calendar_event_time_html.php

<?php

add_filter('FHEE__EE_Calendar__get_calendar_events__event_time_html', 'tw_ee_filter_calendar_event_time_html', 10, 3);
function tw_ee_filter_calendar_event_time_html( $html, $datetime, $event ) {
    // Don't show event times if the event has a 'hide-event-times' custom field set.
    if( get_post_meta( $event->ID(), 'hide-event-times', true ) ) {
        return false;
    }
    return $html;
}