XFree - free client data

data      Specifies the data that are to be freed.

       The  XFree  function is a general-purpose Xlib routine that frees the specified data.  You must use it to
       free any objects that were allocated by Xlib, unless an alternate function is  explicitly  specified  for
       the object.

       If data is NULL, no operation is performed.

       XFree - free client data

Xlib-CLanguageXInterface

X Version 11                                      libX11 1.8.12                                         XFree(3)

       int XFree(void *data);