This is a Windows 7 question, but I’m hoping the answer is the same as
for Vista.

I'm the sole user of my Windows 7 Home Premium 64 computer. There is
no security problem of misuse by others.

By default, the Windows 7 file structure has set up as users:

All Users
Default
Default User
PT
Public

Whenever I either reboot the computer, or whenever it awakens from a
nap, I'm presented with a login screen with an icon for PT which I
must click to open the desktop.

Is there a simple way to eliminate this login screen?