Not sure what you're asking about closing accounts - if it is a website redesign, its a case of modifying the files on the server...no accounts involved.
When I do a website redesign, sometimes I used the existing build, sometimes I modify the build & sometimes I build it from scratch...you have to make that call based on the website in question & how well it has been built in the first place....and whether your new design can be applied to the existing code or not.