Moving WordPress from subdirectory to root

I have had my blog installed in a subdirectory and am trying to move it to the root directory of my URL. ie, from https://www.scotsheraldry.com/blog to https://www.scotsheraldry.com

I have installed WordPress into the root directory successfully but I cannot get it to point at the old MySQL database, I just get a virgin WordPress install database. I still have the old sub directory blog installed which accesses the old database but the new one does not. What am I doing wrong?