I want to remove a folder from my WordPress URL in a particular case:
From:
http://capitulardesign.com.br/blog/portfolio/70-anos-sinduscon/
To:
http://capitulardesign.com.br/portfolio/70-anos-sinduscon/
But the rule must work only on /blog/portfolio/ cases. The WordPress is installed on /blog/ folder and the normal website (custom PHP pages mixed with WordPress Codex codes) is in the root folder. 
Plus: The /portfolio/ is a Custom Post Type taxonomy.
 
     
     
     
    