Is there any way to remove an old home user name from 4 computers ago? I followed the procedure and lost all of my contents and apps.

I followed the procedure on this blog to change the home user name that was copied from four computers ago. All of the contents are mine, and I am the only user of the computer, and on the "users and groups" on system preference, only I appear. Yet, the home user's name appears as always the wrong person's name. I created a new user under my name, copied the contents, then went to erase the home user, only to find that I can never erase the home user. There is no way to redesignate the home user either. After a lot of searching, I found the instructions in this blog. I created another admin user and changed the home user name as directed. A window popped up and told me to restart. When I restarted, the computer turned on without any contents in it. It was completely erased. Nobody warned me that the computer will be completely erased. I had to copy from a backup SSD. I wasted SO MUCH time and I have this incredibly annoying wrong name still appearing as the home user.