Hi,

Please go to file: app/design/frontend/default/sns_i8style/template/page/html/header.phtml to edit. Example: replace the bellow code:

<!-- BEGIN: Logo -->
<div class="header-left">
	<h1 id="logo">
		<a title="<?php echo $this->getLogoAlt() ?>" href="<?php echo $this->getUrl('') ?>">
			<?php
			if(Mage::getStoreConfig('design/header/logo_src')!=''){ ?>
				<img src="<?php echo $this->getLogoSrc(); ?>" alt="<?php echo $this->getLogoAlt() ?>" />
			<?php
			} ?>
			<span><?php //echo $this->getWelcome(); ?></span>
		</a>
	</h1>
</div>
<!-- END: Logo -->
<div class="header-right">
    <div id="sns_mainnav">
    	<?php echo $this->getChildHtml('mainmenu'); ?>
    </div>
    <div class="block_topsearch">
    	<?php echo $this->getChildHtml('topSearch') ?>
    </div>
</div>

by:

<!-- BEGIN: Logo -->
<div class="header-left">
	<h1 id="logo">
		<a title="<?php echo $this->getLogoAlt() ?>" href="<?php echo $this->getUrl('') ?>">
			<?php
			if(Mage::getStoreConfig('design/header/logo_src')!=''){ ?>
				<img src="<?php echo $this->getLogoSrc(); ?>" alt="<?php echo $this->getLogoAlt() ?>" />
			<?php
			} ?>
			<span><?php //echo $this->getWelcome(); ?></span>
		</a>
	</h1>
</div>
<!-- END: Logo -->
<div class="header-right">
    <div class="block_topsearch">
    	<?php echo $this->getChildHtml('topSearch') ?>
    </div>
</div>
<div id="sns_mainnav" class="col-md-12">
    	<?php echo $this->getChildHtml('mainmenu'); ?>
</div>

Thanks!