Copy the header.php of main theme and paste it at child theme, then edit it and find
COPY CODE
<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
COPY CODE
<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'); ?>">