使用.htaccess屏蔽/更改网址

I already search regarding this but the result is not what I want. I hope someone can help me on this. Thanks in advance.

I would like to change/mask url using .htaccess from

http://localhost/ecwp/eccube/html/wpss/forum 

to

http://localhost/ecwp/eccube/html/forum 

This is my folder directory(i'm using XAMPP):-

• htdocs
  • ecwp
    • eccube
      • html
        • wpss->forum under this wp themes
        • .htaccess
      • data

For wpss, I'm using wordpress with permalink setting :

http://localhost/ecwp/eccube/html/wpss/archives/123

Here is .htaccess code:-

RewriteEngine On
RewriteRule ^forum/ http://localhost/ecwp/eccube/html/wpss/forum [L]

When running this code,

http://localhost/ecwp/eccube/html/forum 

will redirect go to

http://localhost/ecwp/eccube/html/wpss/forum

RewriteEngine On
RewriteRule ^forum(.*)$ http://localhost/ecwp/eccube/html/wpss/forum/$1 [L]