You can not remove this symbol, because it's used for mod rewrite functionality. But you can change it:
***Open templates/yourTemplate/footer.tpl and find code***
<!-- footer start -->
<div class="bottom-left">
<div class="bottom">
<div class="bottom-content">
{foreach from=$menus item=menu_item name=bottom_menus}
{in_array_exist def=2 values=$menu_item.menus}
{if $result_valid}
{assign var="inc" value=$inc+1}
{if $inc eq $menu_item.num_bottom}
{assign var="divider" value=""}
{else}
{assign var="divider" value=" | "}
{/if}
{assign var="page_title" value='page_'|cat:$menu_item.id|cat:'_name'}
{if $menu_item.unique_url}
<a href="{$menu_item.unique_url}"{if $menu_item.nofollow eq '1'} rel="nofollow"{/if}>{$menu_item.title}</a>
{else}
{if $config.mod_rewrite}
<a href="{$config.base}{$config.dir}p{$menu_item.name}.html"{if $menu_item.nofollow eq '1'} rel="nofollow"{/if}>{$menu_item.title}</a>
p - change it to your symbol.
***Save changes***
***Open .htaccess and find rule***
# mod_rewrite rules for additional pages
RewriteRule ^p(.*).html$ page.php?name=$1 [QSA,L]
p - change it to your symbol.
***Save changes***