The Rectangular Selection tool lets you draw an outline around a rectangular block of pixels for Copying, moving, transformation, or deletion.
Deleting a selection replaces all of the selected pixels with the current Background color. So, first, set the Background color to the desired color (black).
Then engage the Rectangular Selection tool (see Figure 3 above). Drag the mouse cursor across the area you want to remove to form the selection rectangle. You don't have to select exactly all of it in one goyou can do a couple, smaller operations.
Here's some of the area we're getting rid of selected. Note that I've set the Background color to black. (The Foreground color is also black.):
Figure 4 Some pixels are selected in the top-left corner of the image.
Press the
Delete key to delete the selected area, which replaces it with the Background color.
Figure 5 The result after deleting the selected pixels.
You can repeat selecting areas and deleting them until the areas you want removed are all gone.