If you only need a specific part of an image, you can use the Crop function within the Assets overview.
To crop an image:
Select the image you want to crop from the Assets overview.
The image will open in full-screen view.
In the top-right corner, hover over the “Download file” button.
From the dropdown, click “Crop”.
The image will reload slightly larger, ready for selection. When you hover over the image, your cursor will change.
Click and drag to select the area you want to crop.
The selected area will appear brighter than the rest of the image.
Once satisfied with your selection, click the “Download selection” button in the top-right corner. Your cropped image will be downloaded automatically.