PS: I've tried using 0x00000000, 0 and "0" but none of them has worked.
PPS: Information on the the SpecialAccounts registry key.
NSIS Script:
; Script generated by the HM NIS Edit Script Wizard.
; HM NIS Edit Wizard helper defines
!define PRODUCT_NAME "!Tech Installer"
!define PRODUCT_VERSION "1.1"
!define PRODUCT_PUBLISHER "Swall's Business Consultants"
!define PRODUCT_WEB_SITE "http://www.swallsbc.com"
Name "${PRODUCT_NAME} ${PRODUCT_VERSION}"
OutFile "D:\Temp\TechSetup.exe"
RequestExecutionLevel admin
InstallDir "C:\"
Icon "D:\Temp\SwallsIconDownArrow.ico"
Section "MainSection" SEC01
WriteRegDWORD HKLM "Software\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList" "ITSupport" 0x00000000
SectionEnd
Section -Post
SetAutoClose true
SectionEnd