(Make sure there are no settings already applied to the Crop tool.) Crop to suit your purpose. Make sure you crop at least one line into the top and bottom of the image, as the first line of the image normally starts in the middle of the screen. Don’t be surprised if you have to crop quite a bit from the sides.
(Hint: hold down the Ctrl key on the Mac, Alt on Windows, to enable finer control of the crop.)