I currently have my ee site on www.christatwork.org.uk/dev/

I now want to remove the dev folder because the site is going live. What’s best way to change it?

A couple of ways to do it.  I think the easiest is to just move the main index.php and path.php up a level, edit the path.php file so that it still points to the system folder (generally meaning- add another dot to the path) and the frontend should now resolve one level higher. 

If the only file named index.whatever is the index.php file?  The default template’s index template will show up under mysite.com - or if you have an index.htm or something you want to leave in place, you can always add an htaccess file that will serve the index.php file up by default (instead of .html or something- which is generally the default).

Or- you can move the whole thing up a level- but the above is a bit easier IMO.

Make sense?