You are able to block specific IP addresses by using your .htaccess file.
You can find your .htaccess file in your websites directory (usually httpdocs or public_html).If the files does not exist you can create a .htaccess file and add the following script replacing 168.1.1.1 with the IP address you are looking to block:
order allow,deny deny from 168.1.1.1 allow from all
Please then note that all users using that IP address will be unable to access your website.