This example calls WinQuerySwitchHandle to get the Task List handle of a frame window, and then calls WinRemoveSwitchEntry to remove it.

#define INCL_WINSWITCHLIST
#include <OS2.H>
HAB hab;
HWND hwndFrame;
HSWITCH hswitch;
SWCNTRL swctl;

hswitch = WinQuerySwitchHandle(hwndFrame, 0);
WinRemoveSwitchEntry(hswitch);