Deregister the win32 window class from an SDL_RegisterApp call.
This can be called to undo the effects of SDL_RegisterApp.
Most applications do not need to, and should not, call this directly; SDL will call it when deinitializing the video subsystem.
It is safe to call this multiple times, as long as every call is eventually paired with a prior call to SDL_RegisterApp. The window class will only be deregistered when the registration counter in SDL_RegisterApp decrements to zero through calls to this function.
This function is available since SDL 3.0.0.