\param env the environment to modify.
\param name the name of the variable to unset.
\returns true on success or false on failure; call SDL_GetError() for more
information.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.
Clear a variable from the environment.
\param env the environment to modify. \param name the name of the variable to unset. \returns true on success or false on failure; call SDL_GetError() for more information.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.
\sa SDL_GetEnvironment \sa SDL_CreateEnvironment \sa SDL_GetEnvironmentVariable \sa SDL_GetEnvironmentVariables \sa SDL_SetEnvironmentVariable \sa SDL_UnsetEnvironmentVariable