How to remove featured images from Portfolio posts in RokoPhoto

Please make sure that you're using a child theme with your Parallax One theme. Create a new single-portfolio.php file, and use the following code in it:

<?php get_header(); ?>

    <!-- Blog Posts
    ================================================== -->
    <?php get_sidebar('top'); ?>
    <div class="blog">
        <div class="container">
            <div class="row">

            <?php if ( have_posts() ) : ?>

                <?php while ( have_posts() ) : the_post(); ?>
                        <?php get_template_part( 'content', 'portfolio'); ?>
                <?php endwhile; ?>

            <?php else : ?>
                <?php get_template_part( 'content', 'none' ); ?>
            <?php endif; ?>

            </div>
        </div>
    </div>

    <?php get_sidebar('bottom'); ?>

<?php get_footer(); ?>

Now, create a content-portfolio.php file in your child theme and add the following code in it:

                <!-- Blog post -->
                <div <?php post_class('blog-post'); ?> id="post-<?php the_ID(); ?>">
                    <div class="col-lg-8 col-lg-offset-2">
                        <div class="post wow fadeIn" data-wow-duration="2s">
                            <h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
                            <ul class="list-inline">
                                <li><?php _e( 'Post By:', 'rokophoto' ); ?> <?php the_author_posts_link(); ?></li>
                                <li><?php _e( 'Date:', 'rokophoto' ); ?> <time><?php the_time( get_option( 'date_format' ) ); ?></time></li>
								<?php if ( has_category()) : ?>
									<li><?php _e( 'Category:', 'rokophoto' ); ?> <?php the_category(', '); ?></li>
								<?php endif;?>
                                <li><?php the_tags('Tags: ', ', '); ?></li>
                            </ul>
							<div class="post-content">
								<?php the_content(); ?>
								<?php wp_link_pages(); ?>
							</div>
                        </div>
                    </div>
                    <div class="clearfix"></div>
                </div>

That will do the job!.