You can use Resource Hacker (ResHacker.exe) to do it. As Bongo mentioned you need to edit the authui.dll found in the system32 folder.
First the most important thing to do is to back up "C:\Windows\System32\authui.dll" before you do anything and learn how to replace it in case of not being able to boot into Windows after modding.
I tested it by making a copy of authui.dll then opening the copy in Reshack (2nd copy, not the backup).
In Reshack press CTRL+F to open the find text box and find
<ZoomableElement id="atom(Overlay)" layoutpos="client" />
and replace with
<ZoomableElement id="atom(Overlay)" layoutpos="none" />
The search term is found in the first 3 UIFILE folders but I only needed to change the first one, see image below.
After replacing the text click Compile Script at the top of the window then click file save, not save as, I've had problems with save as.
Now you need to take ownership of "C:\Windows\System32\authui.dll". If you don't know how here is one way that makes it easy - Take Ownership Shortcut
Next open the cmd prompt and type or copy,
taskkill /F /IM Explorer.exe
xcopy /vqy "[YOUR MODDED FILE PATH]\authui.dll" "C:\Windows\System32\*.*"
This will kill explorer before replacing the original authui.dll with your modded one then restart explorer.