How to Delete the Link from the Website Logo

Copy the header.php of main theme and paste it at child theme, then edit it and find

<a href="<?php echo get_home_url(); ?>"><img id="logo_img" src="<?php echo sq_option('logo',get_template_directory_uri().'/assets/images/logo.png'); ?>" width="294" height="108" alt="<?php bloginfo('name'); ?>"></a>

Replace it with

<img id="logo_img" src="<?php echo sq_option('logo',get_template_directory_uri().'/assets/images/logo.png'); ?>" width="294" height="108" alt="<?php bloginfo('name'); ?>">