Best way to switch my existing sub-directory V1 install to my V2 redesign install?

I have the current version of my site running from a subdirectory called, say, v1. I used the ‘copy DO NOT MOVE!’ method to run this from it’s subdirectory but look like it’s the root. I now have a fully functional redesign running in another subdirectory, v2. It shares nothing with v1, including the database.

What is the best way to switch from v1 to v2?

Do I delete the v1 index.php from the root, then basically start over the instructions for changing the URLs in v2 WordPress admin, copying in the v2 index.php, then re-edit the htaccess to point to v2?

Or, to make this easier in future should I decide to completely overhaul everything again, should I try the option for simply pointing the root at the subdirectory, as is recommended for a site that changes design each year? They both seem to do the same thing, is one method better than the other in my case?