how to move wp into other folder?

Please help to solve my problem as below.
In order to keep my currnet site running, I installed the wp2.7 onto
https://www.xxx.com/blog/

now, I like to move it back to https://www.xxx.com/

please anyone tell me where to change the url in the original blog?
(because, when I moved all my stuffs into https://www.xxx.com/, all functions lost the original urg, which is https://www.xxx.com/blog/)

Thanks