Cancel an existing key remap in autohotkey - windows

Question

I have a AutoHotKey script that asks me if I want to remap my Win keys to Ctrl or cancel their remapping, thus making them Win keys again.
However I cannot find a way to cancel the remap. If I use the command LWin::Lwin I get the error message that there is a "duplicate key".
I'm new to AutoHotKey, but I did search first, so please don't bite my head off is this is a stupid question. (It is a Lenovo laptop with Windows7-64).
Here's the script:
MsgBox, 4, , Remap CTRL for Desktop Keyboard?
IfMsgBox, Yes
LWin::LCtrl
RWin::RCtrl
return
; Otherwise, the user picked No
; LWin::LWin
; RWin::RWin
; return

Answer 1

Various ways.
Create a hotkey to close ahk, e.g. ^!x::ExitApp = [Ctrl]+[Alt]+[x]
Create a hotkey to disable/enable all hotkeys e.g. f12::suspend
Create hotkeys that ONLY work in a specific appliaction.
Here are all suggestions combined.
Under normal circumstances: LWin::LCtrl and RWin::RCtrl are active, Unless you pressed F12. You can in AHK_L set variables that can be used in #If (Var = 1), where you can define Hotkeys that only work when that variable is set to 1 (true).
SetTitleMatchMode, 2 ; Allow the use of a portion of the wintitle
F12::
Suspend
If A_IsSuspended
TrayTip, HotKeys, Off, 3, 0
Else
TrayTip, HotKeys, On, 3, 0
Return
^!x::ExitApp
LWin::LCtrl
RWin::RCtrl
F1::MsgBox, Normal Mode
#IfWinActive, Window title
F1::MsgBox, Window X is active
F2::MsgBox, You pressed F2 inside Window x
#IfWinActive
Toggle := False
F10::Toggle := !Toggle ; Turns Mouse button ON|Off
#if Toggle ; ONLY worls in AHK_L
LButton::Return ; Disables Mouse button
#if

Answer 2

Here's a version you can drive from the command line:
; Allow the script to be reloaded multiple times
#SingleInstance force
; Check the command line for input
NumberOfParameters = %0%
; If any command line param was passed then just unload the mappings
If ( NumberOfParameters > 0 )
{
MsgBox Command line parameter was passed, unloading...
ExitApp
}
Else
{
; Let's ask the user what they want to do
MsgBox, 4, , Remap CTRL for Desktop Keyboard?
IfMsgBox, Yes
{
; If yes, then remap
MsgBox Keys have been mapped.
}
Else
{
; If no, then unload
MsgBox Unloading mapping.
ExitApp
}
}
; Keys will be mapped so long as the script remains resident
LWin::LCtrl
RWin::RCtrl