There are a few ways ways to make you image black and white using GIMP.
1. Gray Scale
Launch GIMP and go ahead and open your image as a layer. Next, head to Image. Hover over Mode and select Grayscale. Once you’re able to view your black and white image, don’t forget to export the image to a file type that best fits your needs. The most common image file types are .png, .jpg, and .jpeg.