How can I make customers filling address info optional?

Hi,

I am new to opencart. The default setting of register process is that customers are required to fill in their address. I want this to be optional, which customers can fill that in later, like when they are checking out. Is there any simple way to achieve this (such as using some setting in the admin page)? If it is something that can only be done by coding, can someone teach me? I think I can still code some PHP. Thanks in advance for any help!

P.S. I don't know if I have posted in the right place or not. Do let me know if I have been in a wrong place and I am sorry about that.

in register.tpl you will find this:
<td><span class="required">*</span> <?php echo $entry_firstname; ?></td>

so this class required needs to be changed.

so modified line will be
<td><?php echo $entry_firstname; ?></td>