How to remove "?" Question Mark from URL in wordpress

Question

Please help me. how to remove "?" in query string url rhino/sub-categories/?category=Hotel like as 'rhino/sub-categories/Hotel' in localhost. it's called data in custom database. So, i want to remove ? from the url. I'm trying htaccess like as-

<IfModule mod_rewrite.c>   
RewriteEngine On   
RewriteBase /rhino/   
RewriteRule ^index\.php$ - [L]   
RewriteRule ^sub-categories/([^.]*)$ sub-categories/?category=$1 [QSA,L]   
RewriteCond %{REQUEST_FILENAME} !-f   
RewriteCond %{REQUEST_FILENAME} !-d   
RewriteRule . /rhino/index.php [L]   
</IfModule>

and try function.php like as:-

function listen_rewrite_action() {   
add_rewrite_tag('%category%','([^/]*)');   
add_rewrite_rule('^sub-categories/([^/]+)$','index.php?pagename=sub-categories&category=$matches[1]','top');  
add_rewrite_rule('^sub-categories/([^/]+)/page/([^/]+)$', 'index.php?pagename=sub-categories&category=$matches[1]&paged=$matches[2]','top');    
}   
add_action( 'init', 'listen_rewrite_action' );

syntax and many more. Please help me how to solve this.