.htaccess and permalinks

Hey peeps,

Thanks for taking a moment to read my topic 🙂

I want to change my permalinks settings from default to post name.
Because of that, wordpress gives me a piece of .htaccess code wich I should
put in my .htaccess file.

When I put this new piece of code in my .htaccess file, should I delete the
old piece of code from the .htaccess file?