Reset/delete post views meta/custom field after X hours or minutes or seconds

Your code for scheduling event isn’t correct, here is the correct one:

function hits_set_zero_schedule() {
  if ( ! wp_next_scheduled( 'hits_set_to_zero') )
    wp_schedule_event( time(), 'daily', 'hits_set_zero' );
}
add_action( 'wp', 'hits_set_zero_schedule' );

function hits_set_zero_func() {
  delete_post_meta( $post_id, 'post_views_count', true );
}
add_action( 'hits_set_zero', 'hits_set_zero_func' );

Also, you can define intervals otherwise than daily by adding a little snippet to your code:

add_filter( 'cron_schedules', 'my_custom_schedule' );
function my_custom_schedule( $schedules ) {
    $schedules[ 'five_minutes' ] = array(
        'interval'          =>  5 * 60,
        'display'           =>  'Once five minutes'
    );

    return $schedules;
}

You can change the interval element in the $schedules element, it’s in seconds.