Termination of running app.

Could anyone please tell me how can i terminate an application that is already running from a VB program? Please note that the application has started outside my program so i don't know its task ID. Also note that i wish to terminate it normally (i.e. request its termination, not force its termination).

TIA

try the FindWindow API to find the window handle of a window of that application.
Then post a WM_CLOSE message to that window