Unregisters a window class, freeing the memory required for the class
#include <WinAPISysWin.au3>
_WinAPI_UnregisterClass ( $sClass [, $hInstance = 0] )
| $sClass | A null-terminated string or a class atom. If $sClass is a string, it specifies the window class name. This class name must have been registered by a previous call to the _WinAPI_RegisterClass() or _WinAPI_RegisterClassEx() function. If this parameter is an atom, it must be in the low-order word of $sClass; the high-order word must be zero. |
| $hInstance | [optional] Handle to the instance of the module that created the class. |
| Success: | True |
| Failure: | False |
Before calling this function, an application must destroy all windows created with the specified class.
All window classes that an application registers are unregistered when it terminates.
_WinAPI_RegisterClass, _WinAPI_RegisterClassEx
Search UnregisterClass in MSDN Library.