No the name Serena is not listed under Administrator or anywhere when I go to the file manager.

However when I login to my PC it is shows as the correct username and the old username does not show...

I restored the pc to factory settings but that still did not get rid of the files in the old user name.

I deleted the previous user account on a laptop given to me by my friend (Joanne) and changed it to a new name (Serena). This seemed to work and when when I login it is with the new username. However...