Well, it's easiest to crop the photo in Photoshop Elements and then import it into Premiere Elements as a 2500x1875 pixel photo.
Although, if you place the photo on your timeline, right-click on it and uncheck Scale to Frame Size, you can also zoom into an area on your photo by opening Applied Effects/Motion and setting Scale and Position.
It all depends on what you mean by "crop" and what effect you're trying to create.
For cropping am image you can use crop effect available in Transform effect category in Premiere Elements 14.
In this effect, you can select the amount to be cropped from each side.
Please revert back if you still face any issue.