This function removes a presentation parameter associated with the window hwnd.

#define INCL_WINSYS /* Or use INCL_WIN, INCL_PM, */
#include <os2.h>

HWND     hwnd;        /*  Window handle whose presentation is to be change. */
ULONG    idAttrType;  /*  Type of presentation parameter attribute to be removed. */
BOOL     rc;          /*  Success indicator. */

rc = WinRemovePresParam(hwnd, idAttrType);