Moving from subdomain to root

Hi

I’ve found instructions explaining how to move to a new domain, or from a subdirectory, but not subdomain. I’m replacing an existing Jopomla site with a WordPress equivalent for a friend. The Joomla site is in the httpdocs folder… I asssume I can delete everything here before proceeding. The urls are:

http://www.bristolspanish.co.uk/ (old site)
http://newsite.bristolspanish.co.uk/ (new site)

Any help gratefully received.

Cheers

Jez