Follow the next steps in order to remove the sidebar from gallery page manually via FTP (for gallery template only):
- Download and install FTP client (for example, Filezilla).
- Open FTP client and enter your FTP access credentials (host, username and password) to access files on your server.
- Navigate to 'yourwordpresswebsite/wp-content/themes/yourtheme' directory.
- Find files gallery-template.php (or gallery-pro-template.php) and gallery-single-template.php (or gallery-pro-single-template.php)
- Remove the following line from these files:
<?php get_sidebar(); ?>
- Save changes and clear your browser cache.