How to remove Read Full Story button and expand button instead

Hello,

I’m struggling with removing the ‘Read Full Story’ button at my news section: https://mediaschip.nl/#nieuws. We use the theme PRESENCE v1.0 https://www.designova.net/themes/wordpress/presence/.

I would like to have that button removed, because it links to another page. Instead I would like to have a kind of Toggle button which expands the full text without leaving the page.

Would this be possible? I’m very new to php :(… And searching these forums didn’t clarify things for me.

Thanks in advance!

Here’s my Index.php

<?php
 get_header();
 $presence_options = get_option('presence_wp');
?>
<section class="mast-wrap overlay-close">
	  	<section id="archive-page" class="news page-section presence-page-section" style="background: <?php echo $presence_options['highlight_color'];?>;">
	  		<section class="inner-section">
	  			<?php the_content(); ?>
	  		</section>
	  		<section class="inner-section news-list-wrap add-top-half">
	  			<div class="container">
		  			<?php
		  			$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
					query_posts(array('post_type' => 'post', 'paged' => $paged));

			        if (have_posts()) :
			          while (have_posts()) : the_post();
			      		$presence_post_icon = '';
			      		if(get_post_type( get_the_ID()) == 'post')
		                {
				      		$presence_post_format = get_post_format();
			                switch($presence_post_format)
			                {
			                    case 'audio':
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/audio.png';
			                    break;
			                    case 'video':
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/video.png';
			                    break;
			                    case 'image':
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/image.png';
			                    break;
			                    case 'link':
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/link.png';
			                    break;
			                    case 'quote':
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/quote.png';
			                    break;
			                    default:
			                     $presence_post_icon = get_stylesheet_directory_uri().'/images/post_format/default.png';

			                    break;
			                }
			            }

			        ?>
			        <div class="row news-list-item">
						<article class="col-md-3 text-left news-inner-content grey-bg wow slideInLeft">
							<h4><span class="news-date color"><?php the_time('dS');?></span> <br/><span class="news-month"><?php the_time('F');?></span> <?php the_time('Y');?></h4>
							<h6 class="news-author color"><?php _e('by', 'presencelang');?> <?php the_author(); ?></h6>
							<div class="post-icons"><?php if(is_sticky()){ ?><img src="<?php echo get_stylesheet_directory_uri().'/images/post_format/sticky.png'; ?>" alt="<?php echo get_bloginfo('name'); ?>" /><?php } ?><img src="<?php echo $presence_post_icon; ?>" alt="<?php echo get_bloginfo('name'); ?>" /></div>
						</article>
						<article class="col-md-9 text-left news-inner-content right-content-area wow slideInRight">
							<h3 class=""><?php the_title(); ?></h3>
							<div class="liner align-left liner-small"><span class="highlight-bg"></span></div>
							<p><?php  echo presence_clean(the_excerpt(), 75); ?></p>
							<div class="clearfix"></div>
							<a class="btn btn-presence btn-presence-color presence-ease" href="<?php the_permalink(); ?>"><?php _e('Read Full Story', 'presencelang');?></a>
						</article>
					</div>
			        <?php
			          endwhile;
			        endif;
			        wp_reset_query();
			        ?>
			        <div class="clear"></div>
		            <?php presence_getpagenavi(); ?>
		    	</div>
	  		</section>
	  	</section>
	</section>
<?php
get_footer();
?>