Hi,
You need to use FTP to access your server.
Go to wp-content/themes/
Find your Hueman theme and child theme, download a copy each as backup to your PC.
Next, use FTP to open up the file that you were editing previously, replace back with original codes.
Or you can delete the whole Hueman theme and re-install via WordPress admin.
If you do not know how to use FTP, you will have to contact your web hosting company for help.
Remember to ask them to backup a copy for you before deleting. So that you have a reference of your customizations.
In the future, please do not edit Hueman theme, do all customizations in a child theme.
Thank you.