Need API to Close any application window irrespective of whether it is

[SubratCpp]

Hi all,
I Need API to Close any application window irrespective of whether it is active or not using C++ Win32.

Ex:
After installing toolbar, open IE.If trying to close IE, it'll not allow us to close it unless we are interacting with toolbar window.

But I need to close IE without interacting with toolbar using c++ Win32.

FYI: Manually we can do it through 'Task Manager'.

Please help me in this regard.

Thanks...