Hide left column when autentication page is showed

[joseplj]

Hello,

 

I'm trying to use the latest free prestashop template 1.4.5 with prestashop 1.4.5 and I'm having a problem, once I click to "autentication" link which goes to the sample place as here :

http://demo.prestashop.com/template15/authentication.php?back=my-account.php

 

the left column with all the categories, and all the other modules still there, this makes to put some parts of this page over the right column.

What I have to do to hide the left column once one goes to this page?

 

Many thans !

Joseph