This function empties the clipboard, removing and freeing all handles to data that is in the clipboard.

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

HAB     hab;  /*  Anchor-block handle. */
BOOL    rc;   /*  Success indicator. */

rc = WinEmptyClipbrd(hab);