XYGraph__Delete (ul_pbar_graphics)

 *  Synopsis:
 *    #include <ul_pbar_graphics:xygraph.h>
 *
 *    TXYGraph__Result XYGraph__Delete( void )
 *
 *  Function intent:
 *    XYGraph__Delete() erases the X-Y graph display display and deletes
 *    any XYGraph allocated data structures.  XYGraph__DisplayGraph() must have
 *    been called prior to XYGraph__Delete().
 *  Function parameters:
 *    none
 *  Function return value:
 *    CBS_OK		success
 *    else 		wn_xxx() function error status