Moving b2evolution to a different folder on you server is extremely easy.

Suppose you were on http://mydomain.com/b2evolution/ and you now want to be on http://mydomain.com/blog/ or even http://mydomain.com/.

All you need to do is move your files on the server to the correct location and then let b2evolution know about its new home.

You do this by editing the Baseurl in your /conf/_basic_config.php file. In there you will find a line like:

$baseurl = 'http://mydomain.com/b2evolution/';

Change this to reflect the new location. For example:

$baseurl = 'http://mydomain.com/';