To make a window smaller in a Windows platform, you need to press the Windows + Down key from your keyboard while the window is active. After you did this, you can go to the bottom right corner of the window, and while the cursor is changed into a two-way arrow, left click and drag the window until you reached the desired size. If you can't do this, it's possible that the application doesn't allow window modification. In this case, there is nothing that you can do.