Howto block a visitor of your website using .htaccess.

First of all you will need to know the IP of the visitor you are going to block.
Once you have the IP you can create the following .htaccess file:

order allow,deny
deny from XXX.XXX.XXX.XXX
deny from XXX.XXX.XXX.XXX
allow from all

XXX.XXX.XXX.XXX: IP of a visitor who is going to be banned from your website.