Hello Antonio,
I am really sorry for the delay of this reply as it is a weekend for us here. Unfortunately right now this is not configurable but you can edit the theme file /components/com_easysocial/themes/wireframe/groups/category.item.php and remove the block of codes below,
<div class="es-widget">
<div class="es-widget-head">
<div class="pull-left widget-title"><?php echo JText::_( 'COM_EASYSOCIAL_GROUPS_RANDOM_ALBUMS' );?></div>
</div>
<div class="es-widget-body">
<?php if ($randomAlbums) { ?>
<ul class="widget-list-grid">
<?php foreach( $randomAlbums as $album ){ ?>
<li>
<div class="es-avatar-wrap">
<a href="<?php echo $album->getPermalink();?>" class="es-avatar es-avatar-sm"
data-original-title="<?php echo $this->html( 'string.escape' , $album->get( 'title' ) );?>"
data-es-provide="tooltip"
data-placement="bottom"
>
<img alt="<?php echo $this->html( 'string.escape' , $album->get( 'title' ) );?>" src="<?php echo $album->getCover( 'square' );?>" />
</a>
</div>
</li>
<?php } ?>
</ul>
<?php } else { ?>
<div class="fd-small">
<?php echo JText::_('COM_EASYSOCIAL_GROUPS_NO_ALBUMS_HERE'); ?>
</div>
<?php } ?>
</div>
</div>